wireless: ath9k-htc: only load firmware in need

It is not necessary to hold the firmware memory during the whole
driver lifetime, and obviously it does waste memory. Suppose there
are 4 ath9k-htc usb dongles working, kernel has to consume about
4*50KBytes RAM to cache firmware for all dongles. After applying the
patch, kernel only caches one single firmware image in RAM for
all ath9k-htc devices just during system suspend/resume cycle.

When system is ready for loading firmware, ath9k-htc can request
the loading from usersapce. During system resume, ath9k-htc still
can load the firmware which was cached in kernel memory before
system suspend.

Cc: ath9k-devel@lists.ath9k.org
Cc: "Luis R. Rodriguez" <mcgrof@qca.qualcomm.com>
Cc: Jouni Malinen <jouni@qca.qualcomm.com>
Cc: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Cc: Senthil Balasubramanian <senthilb@qca.qualcomm.com>
Cc: "John W. Linville" <linville@tuxdriver.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.h b/drivers/net/wireless/ath/ath9k/hif_usb.h
index 487ff65..51496e7 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.h
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.h
@@ -85,12 +85,14 @@
 };
 
 #define HIF_USB_START BIT(0)
+#define HIF_USB_READY BIT(1)
 
 struct hif_device_usb {
 	struct usb_device *udev;
 	struct usb_interface *interface;
 	const struct usb_device_id *usb_device_id;
-	const struct firmware *firmware;
+	const void *fw_data;
+	size_t fw_size;
 	struct completion fw_done;
 	struct htc_target *htc_handle;
 	struct hif_usb_tx tx;