powerpc/pseries: Enable support for ibm,drc-info property

Advertise client support for the PAPR architected ibm,drc-info device
tree property during CAS handshake.

Fixes: c7a3275e

 ("powerpc/pseries: Revert support for ibm,drc-info devtree property")
Signed-off-by: Tyrel Datwyler <tyreld@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1573449697-5448-11-git-send-email-tyreld@linux.ibm.com