target-arm: Fix bit test in sp_el0_access

Static code analyzers complain about a dubious & operation used for a
boolean value. The code does not test the PSTATE_SP bit as it should.

Cc: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: NStefan Weil <sw@weilnetz.de>
Message-id: 1406359601-25583-1-git-send-email-sw@weilnetz.de
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

target-arm/helper.c

@@ -1853,7 +1853,7 @@ static uint64_t aa64_dczid_read(CPUARMState *env, const ARMCPRegInfo *ri)
 
 static CPAccessResult sp_el0_access(CPUARMState *env, const ARMCPRegInfo *ri)
 {
-    if (!env->pstate & PSTATE_SP) {
+    if (!(env->pstate & PSTATE_SP)) {
         /* Access to SP_EL0 is undefined if it's being used as
          * the stack pointer.
          */