rtlwifi: Fix some warnings/bugs

Some compiler/architecture combinations generate some warnings that are
not seen on my main system. Two of the "warnings" about unitialized variables
are really bugs.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/rtlwifi/rtl8192c/fw_common.c b/drivers/net/wireless/rtlwifi/rtl8192c/fw_common.c
index 5ef9137..28a6ce3 100644
--- a/drivers/net/wireless/rtlwifi/rtl8192c/fw_common.c
+++ b/drivers/net/wireless/rtlwifi/rtl8192c/fw_common.c
@@ -303,7 +303,7 @@
 	u16 box_reg, box_extreg;
 	u8 u1b_tmp;
 	bool isfw_read = false;
-	u8 buf_index;
+	u8 buf_index = 0;
 	bool bwrite_sucess = false;
 	u8 wait_h2c_limmit = 100;
 	u8 wait_writeh2c_limmit = 100;