PM: sleep: spread "const char *" correctness

Fixed string literals can be referred to as "const char *".

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
[ rjw: Minor subject edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/kernel/power/power.h b/kernel/power/power.h
index ba2094d..32fc89a 100644
--- a/kernel/power/power.h
+++ b/kernel/power/power.h
@@ -32,7 +32,7 @@ static inline int init_header_complete(struct swsusp_info *info)
 	return arch_hibernation_header_save(info, MAX_ARCH_HEADER_SIZE);
 }
 
-static inline char *check_image_kernel(struct swsusp_info *info)
+static inline const char *check_image_kernel(struct swsusp_info *info)
 {
 	return arch_hibernation_header_restore(info) ?
 			"architecture specific data" : NULL;
diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c
index 881128b9..cef1542 100644
--- a/kernel/power/snapshot.c
+++ b/kernel/power/snapshot.c
@@ -2023,7 +2023,7 @@ static int init_header_complete(struct swsusp_info *info)
 	return 0;
 }
 
-static char *check_image_kernel(struct swsusp_info *info)
+static const char *check_image_kernel(struct swsusp_info *info)
 {
 	if (info->version_code != LINUX_VERSION_CODE)
 		return "kernel version";
@@ -2176,7 +2176,7 @@ static void mark_unsafe_pages(struct memory_bitmap *bm)
 
 static int check_header(struct swsusp_info *info)
 {
-	char *reason;
+	const char *reason;
 
 	reason = check_image_kernel(info);
 	if (!reason && info->num_physpages != get_num_physpages())