usb: gadget: Remove File-backed Storage Gadget (g_file_storage).

The File-backed Storage Gadget (g_file_storage) gadget has been replaced
with Mass Storage Gadget (g_mass_storage) which uses the composite
framework.  This commit removes g_file_storage (and most references to it).

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/gadget/pxa27x_udc.h b/drivers/usb/gadget/pxa27x_udc.h
index a1d268c..79d81a4 100644
--- a/drivers/usb/gadget/pxa27x_udc.h
+++ b/drivers/usb/gadget/pxa27x_udc.h
@@ -418,7 +418,7 @@
  * @irq: udc irq
  * @clk: udc clock
  * @usb_gadget: udc gadget structure
- * @driver: bound gadget (zero, g_ether, g_file_storage, ...)
+ * @driver: bound gadget (zero, g_ether, g_mass_storage, ...)
  * @dev: device
  * @mach: machine info, used to activate specific GPIO
  * @transceiver: external transceiver to handle vbus sense and D+ pullup