b43: Fix error in cordic routine

commit 8ea3819c0bbef57a51d8abe579e211033e861677 upstream.

The cordic routine for calculating sines and cosines that was added in
commit 6f98e62a ("b43: update cordic code to match current specs")
contains an error whereby a quantity declared u32 can in fact go negative.

This problem was detected by Priit Laes who is switching b43 to use the
routine in the library functions of the kernel.

Fixes: 98650454 ("b43: make cordic common (LP-PHY and N-PHY need it)")
Reported-by: NPriit Laes <plaes@plaes.org>
Cc: Rafał Miłecki <zajec5@gmail.com>
Cc: Stable <stable@vger.kernel.org> # 2.6.34
Signed-off-by: NLarry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: NPriit Laes <plaes@plaes.org>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/wireless/broadcom/b43/phy_common.c

@@ -616,7 +616,7 @@ struct b43_c32 b43_cordic(int theta)
 	u8 i;
 	s32 tmp;
 	s8 signx = 1;
-	u32 angle = 0;
+	s32 angle = 0;
 	struct b43_c32 ret = { .i = 39797, .q = 0, };
 
 	while (theta > (180 << 16))