powerpc/85xx: sbc8560 - correct compilation if CONFIG_PHYS_ADDR_T_64BIT is set

If CONFIG_PHYS_ADDR_T_64BIT is set, compilation of sbc8560 fails with
the following error:

arch/powerpc/platforms/85xx/sbc8560.c: In function ‘sbc8560_bdrstcr_init’:
arch/powerpc/platforms/85xx/sbc8560.c:286: error: format ‘%x’ expects type ‘unsigned int’, but argument 2 has type ‘resource_size_t’

Fix that by using %pR format instead of just printing the start of
resource.

Signed-off-by: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>