ssb: make ssb_sdio_switch_core static

It's used locally only.

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
diff --git a/drivers/ssb/sdio.c b/drivers/ssb/sdio.c
index b2d36f7..2278e43 100644
--- a/drivers/ssb/sdio.c
+++ b/drivers/ssb/sdio.c
@@ -200,7 +200,7 @@
 }
 
 /* host must be already claimed */
-int ssb_sdio_switch_core(struct ssb_bus *bus, struct ssb_device *dev)
+static int ssb_sdio_switch_core(struct ssb_bus *bus, struct ssb_device *dev)
 {
 	u8 coreidx = dev->core_index;
 	u32 sbaddr;