soc: ambiq: fix potential issues

1. fix compile issue when CONFIG_DCACHE=n
2. check null in buf_in_nocache

Signed-off-by: Swift Tian <swift.tian@ambiq.com>

Author: swift-tk

soc/ambiq/apollo5x/soc.c

@@ -8,9 +8,9 @@
 #include <zephyr/cache.h>
 #include <zephyr/logging/log.h>
 #include <zephyr/mem_mgmt/mem_attr.h>
-#ifdef CONFIG_DCACHE
+#ifdef CONFIG_CACHE_MANAGEMENT
 #include <zephyr/dt-bindings/memory-attr/memory-attr-arm.h>
-#endif /* CONFIG_DCACHE */
+#endif /* CONFIG_CACHE_MANAGEMENT */
 
 #ifdef CONFIG_NOCACHE_MEMORY
 #include <zephyr/linker/linker-defs.h>
@@ -48,8 +48,9 @@ void soc_early_init_hook(void)
 	/*
 	 * Set default temperature for spotmgr to room temperature
 	 */
-	am_hal_pwrctrl_temp_thresh_t dummy[32];
-	am_hal_pwrctrl_temp_update(25.0f, dummy);
+	am_hal_pwrctrl_temp_thresh_t dummy;
+
+	am_hal_pwrctrl_temp_update(25.0f, &dummy);
 
 	/* Enable Icache*/
 	sys_cache_instr_enable();
@@ -63,6 +64,10 @@ bool buf_in_nocache(uintptr_t buf, size_t len_bytes)
 {
 	bool buf_within_nocache = false;
 
+	if (buf == 0 || len_bytes == 0) {
+		return buf_within_nocache;
+	}
+
 #if CONFIG_NOCACHE_MEMORY
 	/* Check if buffer is in nocache region defined by the linker */
 	buf_within_nocache = (buf >= ((uintptr_t)_nocache_ram_start)) &&