staging: wfx: fix missing 'static' statement

The function get_firmware() is only used from fwio.c. It can be declared
static.
Signed-off-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/20200505123757.39506-10-Jerome.Pouiller@silabs.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wfx/fwio.c

@@ -99,8 +99,8 @@ static int sram_write_dma_safe(struct wfx_dev *wdev, u32 addr, const u8 *buf,
 	return ret;
 }
 
-int get_firmware(struct wfx_dev *wdev, u32 keyset_chip,
-		 const struct firmware **fw, int *file_offset)
+static int get_firmware(struct wfx_dev *wdev, u32 keyset_chip,
+			const struct firmware **fw, int *file_offset)
 {
 	int keyset_file;
 	char filename[256];