[Blackfin] arch: make the mask explicit rather than writing a negative number in hex

Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

arch/blackfin/mach-common/lock.S

@@ -174,7 +174,7 @@ ENTRY(_cache_lock)
 	CLI R3;
 
 	R7 = [P1];
-	R2 = 0xFFFFFF87 (X);
+	R2 = ~(0x78) (X);	/* mask out ILOC */
 	R7 = R7 & R2;
 	R0 = R0 << 3;
 	R7 = R0 | R7;