ARM DPM: share debug reason logic

No point in both ARM11 and Cortex-A8 having private copies
of the logic sorting out e.g. DBG_REASON_WATCHPOINT.

Add and use a shared routine for this ... there's actually
a bunch more debug entry logic that could be shared, this
is just a start on that.  Note that this routine fixes a
bug observed in the ARM11 code, where some abort mode quirks
were displayed as being an unknown debug reason; and also
silences needless ARM11 chatter.

Likewise with private copies of DSCR ... add one to the DPM
struct.  Save it as part of setting DBG_REASON_* so later
patches can switch over to using that copy.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

src/target/arm_dpm.h

@@ -125,6 +125,9 @@ struct arm_dpm {
 	/** Address of the instruction which triggered a watchpoint. */
 	uint32_t wp_pc;
 
+	/** Recent value of DSCR. */
+	uint32_t dscr;
+
 	// FIXME -- read/write DCSR methods and symbols
 };
 
@@ -151,4 +154,6 @@ void arm_dpm_report_wfar(struct arm_dpm *, uint32_t wfar);
 
 #define DSCR_ENTRY(dscr) (((dscr) >> 2) & 0xf)
 
+void arm_dpm_report_dscr(struct arm_dpm *dpm, uint32_t dcsr);
+
 #endif /* __ARM_DPM_H */