ppc: spapr: Enable 2nd DAWR on Power10 pSeries machine

ppc: spapr: Enable 2nd DAWR on Power10 pSeries machine

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. Use KVM_CAP_PPC_DAWR1 capability to find
whether kvm supports 2nd DAWR or not. If it's supported, allow user to set
the pa-feature bit in guest DT using cap-dawr1 machine capability.

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Signed-off-by: Shivaprasad G Bhat <sbhat@linux.ibm.com>
Message-ID: <173708681866.1678.11128625982438367069.stgit@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>