arm: Use different enum for core_type and core_mode

The fields core_type and core_mode use the same enum arm_mode
but encode different information, making the code less immediate
to read.

Use a different enum arm_core_type for the field core_type.
The code behavior is not changed.

Change-Id: I60f2095ea6801dfe22f6da81ec295ca71ef90466
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5258
Tested-by: jenkins

src/target/armv7m.c

@@ -695,7 +695,7 @@ int armv7m_init_arch_info(struct target *target, struct armv7m_common *armv7m)
 	/* Enable stimulus port #0 by default */
 	armv7m->trace_config.itm_ter[0] = 1;
 
-	arm->core_type = ARM_MODE_THREAD;
+	arm->core_type = ARM_CORE_TYPE_M_PROFILE;
 	arm->arch_info = armv7m;
 	arm->setup_semihosting = armv7m_setup_semihosting;