firmware_class: make request_firmware_nowait more useful

Unfortunately, one cannot hold on to the struct firmware
that request_firmware_nowait() hands off, which is needed
in some cases. Allow this by requiring the callback to
free it (via release_firmware).

Additionally, give it a gfp_t parameter -- all the current
users call it from a GFP_KERNEL context so the GFP_ATOMIC
isn't necessary. This also marks an API break which is
useful in a sense, although that is obviously not the
primary purpose of this change.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Cc: Ming Lei <tom.leiming@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Woodhouse <David.Woodhouse@intel.com>
Cc: Pavel Roskin <proski@gnu.org>
Cc: Abhay Salunke <abhay_salunke@dell.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/firmware/dell_rbu.c b/drivers/firmware/dell_rbu.c
index b4704e1..b3a0cf5 100644
--- a/drivers/firmware/dell_rbu.c
+++ b/drivers/firmware/dell_rbu.c
@@ -544,9 +544,12 @@
 {
 	rbu_data.entry_created = 0;
 
-	if (!fw || !fw->size)
+	if (!fw)
 		return;
 
+	if (!fw->size)
+		goto out;
+
 	spin_lock(&rbu_data.lock);
 	if (!strcmp(image_type, "mono")) {
 		if (!img_update_realloc(fw->size))
@@ -568,6 +571,8 @@
 	} else
 		pr_debug("invalid image type specified.\n");
 	spin_unlock(&rbu_data.lock);
+ out:
+	release_firmware(fw);
 }
 
 static ssize_t read_rbu_image_type(struct kobject *kobj,
@@ -615,7 +620,7 @@
 			spin_unlock(&rbu_data.lock);
 			req_firm_rc = request_firmware_nowait(THIS_MODULE,
 				FW_ACTION_NOHOTPLUG, "dell_rbu",
-				&rbu_device->dev, &context,
+				&rbu_device->dev, GFP_KERNEL, &context,
 				callbackfn_rbu);
 			if (req_firm_rc) {
 				printk(KERN_ERR