target/arm/helper: make it clear the EC field is also in hex

..just like the rest of the displayed ESR register. Otherwise people
might scratch their heads if a not obviously hex number is displayed
for the EC field.
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NKONRAD Frederic <fred.konrad@greensocs.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>

target/arm/helper.c

@@ -6857,7 +6857,7 @@ void arm_cpu_do_interrupt(CPUState *cs)
                   new_el);
     if (qemu_loglevel_mask(CPU_LOG_INT)
         && !excp_is_internal(cs->exception_index)) {
-        qemu_log_mask(CPU_LOG_INT, "...with ESR %x/0x%" PRIx32 "\n",
+        qemu_log_mask(CPU_LOG_INT, "...with ESR 0x%x/0x%" PRIx32 "\n",
                       env->exception.syndrome >> ARM_EL_EC_SHIFT,
                       env->exception.syndrome);
     }