Staging: vt6656: fix up built-in compilation together with rt2870

Fix this build error:

  drivers/staging/vt6656/built-in.o: In function `rotr1':
  (.text+0x1a878): multiple definition of `rotr1'
  drivers/staging/rt2870/built-in.o:(.text+0x106c2): first defined here
  drivers/staging/vt6656/built-in.o: In function `tkip_sbox':
  (.text+0x1a848): multiple definition of `tkip_sbox'
  drivers/staging/rt2870/built-in.o:(.text+0x10697): first defined here
  drivers/staging/vt6656/built-in.o: In function `xor_32':
  (.text+0x1ec24): multiple definition of `xor_32'
  drivers/staging/rt2870/built-in.o:(.text+0x111c4): first defined here
  drivers/staging/vt6656/built-in.o: In function `xor_128':
  (.text+0x1ec00): multiple definition of `xor_128'
  drivers/staging/rt2870/built-in.o:(.text+0x111dd): first defined here

Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/staging/vt6656/aes_ccmp.c b/drivers/staging/vt6656/aes_ccmp.c
index b3d367b..f7a3b8f 100644
--- a/drivers/staging/vt6656/aes_ccmp.c
+++ b/drivers/staging/vt6656/aes_ccmp.c
@@ -106,7 +106,7 @@
 
 /*---------------------  Export Functions  --------------------------*/
 
-void xor_128(BYTE *a, BYTE *b, BYTE *out)
+static void xor_128(BYTE *a, BYTE *b, BYTE *out)
 {
 	PDWORD dwPtrA = (PDWORD) a;
 	PDWORD dwPtrB = (PDWORD) b;
@@ -119,7 +119,7 @@
 }
 
 
-void xor_32(BYTE *a, BYTE *b, BYTE *out)
+static void xor_32(BYTE *a, BYTE *b, BYTE *out)
 {
 	PDWORD dwPtrA = (PDWORD) a;
 	PDWORD dwPtrB = (PDWORD) b;