powerpc/watchpoint: Set CPU_FTR_DAWR1 based on pa-features bit

As per the PAPR, bit 0 of byte 64 in pa-features property indicates
availability of 2nd DAWR registers. i.e. If this bit is set, 2nd
DAWR is present, otherwise not. Host generally uses "cpu-features",
which masks "pa-features". But "cpu-features" are still not used for
guests and thus this change is mostly applicable for guests only.
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Tested-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200723090813.303838-7-ravi.bangoria@linux.ibm.com

arch/powerpc/kernel/prom.c

@@ -175,6 +175,8 @@ static struct ibm_pa_feature {
 	 */
 	{ .pabyte = 22, .pabit = 0, .cpu_features = CPU_FTR_TM_COMP,
 	  .cpu_user_ftrs2 = PPC_FEATURE2_HTM_COMP | PPC_FEATURE2_HTM_NOSC_COMP },
+
+	{ .pabyte = 64, .pabit = 0, .cpu_features = CPU_FTR_DAWR1 },
 };
 
 static void __init scan_features(unsigned long node, const unsigned char *ftrs,