mailbox: Fix format and type mismatches in Broadcom PDC driver

Fix format and type mismatches in a couple debug prints in the
Broadcom PDC driver. Use %pad for dma_addr_t and %pa for
resource_size_t.

Signed-off-by: Rob Rice <rob.rice@broadcom.com>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>