Use "%p" to print cmdbuf.

Compilation warning as below:

  CC      spl/drivers/spi/cadence_qspi_apb.o
  LD      spl/lib/built-in.o
drivers/spi/cadence_qspi_apb.c: In function ‘cadence_qspi_apb_indirect_write_setup’:
drivers/spi/cadence_qspi_apb.c:696:18: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]
          cmdlen, (unsigned int)cmdbuf);
Signed-off-by: NLey Foon Tan <ley.foon.tan@intel.com>
Acked-by: NMarek Vasut <marex@denx.de>