block: Constify data passed by pointer to blk_name

blk_name() is not modifying data passed to it through pointer and it
returns also a pointer to const so the argument can be made const for
code safeness.
Signed-off-by: NKrzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/block-backend.c

@@ -420,7 +420,7 @@ void monitor_remove_blk(BlockBackend *blk)
  * Return @blk's name, a non-null string.
  * Returns an empty string iff @blk is not referenced by the monitor.
  */
-const char *blk_name(BlockBackend *blk)
+const char *blk_name(const BlockBackend *blk)
 {
     return blk->name ?: "";
 }

include/sysemu/block-backend.h

@@ -99,7 +99,7 @@ int blk_get_refcnt(BlockBackend *blk);
 void blk_ref(BlockBackend *blk);
 void blk_unref(BlockBackend *blk);
 void blk_remove_all_bs(void);
-const char *blk_name(BlockBackend *blk);
+const char *blk_name(const BlockBackend *blk);
 BlockBackend *blk_by_name(const char *name);
 BlockBackend *blk_next(BlockBackend *blk);
 bool monitor_add_blk(BlockBackend *blk, const char *name, Error **errp);