PM / Sleep: Fix read_unlock_usermodehelper() call.

Commit b298d289
 "PM / Sleep: Fix freezer failures due to racy usermodehelper_is_disabled()"
added read_unlock_usermodehelper() but read_unlock_usermodehelper() is called
without read_lock_usermodehelper() when kmalloc() failed.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

drivers/base/firmware_class.c

@@ -525,8 +525,7 @@ static int _request_firmware(const struct firmware **firmware_p,
 	if (!firmware) {
 		dev_err(device, "%s: kmalloc(struct firmware) failed\n",
 			__func__);
-		retval = -ENOMEM;
-		goto out;
+		return -ENOMEM;
 	}
 
 	if (fw_get_builtin_firmware(firmware, name)) {