staging: wfx: Make function 'sram_write_dma_safe', 'load_firmware_secure' static

Fix sparse warnings:

drivers/staging/wfx/fwio.c:83:5: warning: symbol 'sram_write_dma_safe' was not declared. Should it be static?
drivers/staging/wfx/fwio.c:229:5: warning: symbol 'load_firmware_secure' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: zhengbin <zhengbin13@huawei.com>
Reviewed-by: Jérôme Pouiller <jerome.pouiller@silabs.com>
Link: https://lore.kernel.org/r/1570629030-29888-2-git-send-email-zhengbin13@huawei.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wfx/fwio.c

@@ -80,7 +80,8 @@ static const char * const fwio_error_strings[] = {
  * NOTE: it may also be possible to use 'pages' from struct firmware and avoid
  * bounce buffer
  */
-int sram_write_dma_safe(struct wfx_dev *wdev, u32 addr, const u8 *buf, size_t len)
+static int sram_write_dma_safe(struct wfx_dev *wdev, u32 addr, const u8 *buf,
+			       size_t len)
 {
 	int ret;
 	const u8 *tmp;
@@ -226,7 +227,7 @@ static void print_boot_status(struct wfx_dev *wdev)
 	}
 }
 
-int load_firmware_secure(struct wfx_dev *wdev)
+static int load_firmware_secure(struct wfx_dev *wdev)
 {
 	const struct firmware *fw = NULL;
 	int header_size;