powerpc/papr_scm: Update debug message

Resource struct p->res is assigned later. Avoid using %pR before the resource
struct is assigned.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191202063855.154321-1-aneesh.kumar@linux.ibm.com