md: Fix "strchr" [drivers/md/dm-log-userspace.ko] undefined!

Commit b8313b6d ("dm log: remove incorrect
field from userspace table output") added a call to strstr() with a
single-character "needle" string parameter.

Unfortunately some versions of gcc replace such calls to strstr() by calls
to strchr() behind our back.  This causes linking errors if strchr() is
defined as an inline function in <asm/string.h> (e.g. on m68k):

| WARNING: "strchr" [drivers/md/dm-log-userspace.ko] undefined!

Avoid this by explicitly calling strchr() instead.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/md/dm-log-userspace-base.c

@@ -582,7 +582,7 @@ static int userspace_status(struct dm_dirty_log *log, status_type_t status_type,
 		break;
 	case STATUSTYPE_TABLE:
 		sz = 0;
-		table_args = strstr(lc->usr_argv_str, " ");
+		table_args = strchr(lc->usr_argv_str, ' ');
 		BUG_ON(!table_args); /* There will always be a ' ' */
 		table_args++;