dm raid: don't use 'const' in function return

A newly introduced function has 'const int' as the return type,
but as "make W=1" reports, that has no meaning:

drivers/md/dm-raid.c:510:18: error: type qualifiers ignored on function return type [-Werror=ignored-qualifiers]

This changes the return type to plain 'int'.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Fixes: 33e53f06 ("dm raid: introduce extended superblock and new raid types to support takeover/reshaping")
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-raid.c

@@ -507,7 +507,7 @@ static const char *raid10_md_layout_to_format(int layout)
 }
 
 /* Return md raid10 algorithm for @name */
-static const int raid10_name_to_format(const char *name)
+static int raid10_name_to_format(const char *name)
 {
 	if (!strcasecmp(name, "near"))
 		return ALGORITHM_RAID10_NEAR;