target/arm: Correct MPU trace handling of write vs execute

Correct off-by-one bug in the PSMAv7 MPU tracing where it would print
a write access as "reading", an insn fetch as "writing", and a read
access as "execute".

Since we have an MMUAccessType enum now, we can make the code clearer
in the process by using that rather than the raw 0/1/2 values.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Message-id: 1500906792-18010-1-git-send-email-peter.maydell@linaro.org

target/arm/helper.c

@@ -8558,8 +8558,8 @@ static bool get_phys_addr(CPUARMState *env, target_ulong address,
                                    phys_ptr, prot, fsr);
         qemu_log_mask(CPU_LOG_MMU, "PMSAv7 MPU lookup for %s at 0x%08" PRIx32
                       " mmu_idx %u -> %s (prot %c%c%c)\n",
-                      access_type == 1 ? "reading" :
-                      (access_type == 2 ? "writing" : "execute"),
+                      access_type == MMU_DATA_LOAD ? "reading" :
+                      (access_type == MMU_DATA_STORE ? "writing" : "execute"),
                       (uint32_t)address, mmu_idx,
                       ret ? "Miss" : "Hit",
                       *prot & PAGE_READ ? 'r' : '-',