ipc: Kill bogus dependency on spinlock.h

pruning sched.h dependencies, headers shouldn't pull in more than they
need.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

Author: Kent Overstreet

include/linux/ipc.h

@@ -2,7 +2,7 @@
 #ifndef _LINUX_IPC_H
 #define _LINUX_IPC_H
 
-#include <linux/spinlock.h>
+#include <linux/spinlock_types.h>
 #include <linux/uidgid.h>
 #include <linux/rhashtable-types.h>
 #include <uapi/linux/ipc.h>

include/linux/sched.h

@@ -2139,6 +2139,8 @@ extern bool sched_task_on_rq(struct task_struct *p);
 extern unsigned long get_wchan(struct task_struct *p);
 extern struct task_struct *cpu_curr_snapshot(int cpu);
 
+#include <linux/spinlock.h>
+
 /*
  * In order to reduce various lock holder preemption latencies provide an
  * interface to see if a vCPU is currently running or not.