scripts: generate_rust_analyzer: add missing include_dirs

Commit 8c4555c ("scripts: add `generate_rust_analyzer.py`")
specified OBJTREE for the bindings crate, and `source.include_dirs` for
the kernel crate, likely in an attempt to support out-of-source builds
for those crates where the generated files reside in `objtree` rather
than `srctree`. This was insufficient because both bits of configuration
are required for each crate; the result is that rust-analyzer is unable
to resolve generated files for either crate in an out-of-source build.

  [ Originally we were not using `OBJTREE` in the `kernel` crate, but
    we did pass the variable anyway, so conceptually it could have been
    there since then.

    Regarding `include_dirs`, it started in `kernel` before being in
    mainline because we included the bindings directly there (i.e.
    there was no `bindings` crate). However, when that crate got
    created, we moved the `OBJTREE` there but not the `include_dirs`.
    Nowadays, though, we happen to need the `include_dirs` also in
    the `kernel` crate for `generated_arch_static_branch_asm.rs` which
    was not there back then -- Tamir confirms it is indeed required
    for that reason. - Miguel ]

Add the missing bits to improve the developer experience.

Fixes: 8c4555c ("scripts: add `generate_rust_analyzer.py`")
Signed-off-by: Tamir Duberstein <tamird@gmail.com>
Tested-by: Andreas Hindborg <a.hindborg@kernel.org>
Link: https://lore.kernel.org/r/20250210-rust-analyzer-bindings-include-v2-1-23dff845edc3@gmail.com
[ Slightly reworded title. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

Author: tamird

scripts/generate_rust_analyzer.py

@@ -97,27 +97,27 @@ def append_sysroot_crate(
         ["core", "compiler_builtins"],
     )
 
-    append_crate(
-        "bindings",
-        srctree / "rust"/ "bindings" / "lib.rs",
-        ["core"],
-        cfg=cfg,
-    )
-    crates[-1]["env"]["OBJTREE"] = str(objtree.resolve(True))
+    def append_crate_with_generated(
+        display_name,
+        deps,
+    ):
+        append_crate(
+            display_name,
+            srctree / "rust"/ display_name / "lib.rs",
+            deps,
+            cfg=cfg,
+        )
+        crates[-1]["env"]["OBJTREE"] = str(objtree.resolve(True))
+        crates[-1]["source"] = {
+            "include_dirs": [
+                str(srctree / "rust" / display_name),
+                str(objtree / "rust")
+            ],
+            "exclude_dirs": [],
+        }
 
-    append_crate(
-        "kernel",
-        srctree / "rust" / "kernel" / "lib.rs",
-        ["core", "macros", "build_error", "bindings"],
-        cfg=cfg,
-    )
-    crates[-1]["source"] = {
-        "include_dirs": [
-            str(srctree / "rust" / "kernel"),
-            str(objtree / "rust")
-        ],
-        "exclude_dirs": [],
-    }
+    append_crate_with_generated("bindings", ["core"])
+    append_crate_with_generated("kernel", ["core", "macros", "build_error", "bindings"])
 
     def is_root_crate(build_file, target):
         try: