board/netta/codec.c: Fix GCC 4.6 build warnings

Fix:
codec.c: In function 's_write_BR':
codec.c:1389:15: warning: variable 'v' set but not used
[-Wunused-but-set-variable]
codec.c: In function 's_write_OR':
codec.c:1400:15: warning: variable 'v' set but not used
[-Wunused-but-set-variable]
codec.c: In function 's_write_NR':
codec.c:1411:15: warning: variable 'v' set but not used
[-Wunused-but-set-variable]

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/board/netta/codec.c b/board/netta/codec.c
index c8d31d7..e303aa4 100644
--- a/board/netta/codec.c
+++ b/board/netta/codec.c
@@ -1386,34 +1386,31 @@
 static void s_write_BR(int s_id, unsigned int regno, unsigned int val)
 {
 	unsigned int address;
-	unsigned int v;
 
 	address = 0x70 | (regno & 15);
 	val &= 0xff;
 
-	v = s_transfer_internal(s_id, address, val);
+	(void)s_transfer_internal(s_id, address, val);
 }
 
 static void s_write_OR(int s_id, unsigned int regno, unsigned int val)
 {
 	unsigned int address;
-	unsigned int v;
 
 	address = 0x70 | (regno & 15);
 	val &= 0xff;
 
-	v = s_transfer_internal(s_id, address, val);
+	(void)s_transfer_internal(s_id, address, val);
 }
 
 static void s_write_NR(int s_id, unsigned int regno, unsigned int val)
 {
 	unsigned int address;
-	unsigned int v;
 
 	address = (regno & 7) << 4;
 	val &= 0xf;
 
-	v = s_transfer_internal(s_id, address | val, 0x00);
+	(void)s_transfer_internal(s_id, address | val, 0x00);
 }
 
 #define BR7_IFR			0x08	/* IDL2 free run */