mtd: fsl-quadspi: fix printk() format warning for size_t

Seen when compile-testing on non-32-bit arch:

    CC      drivers/mtd/spi-nor/fsl-quadspi.o
  drivers/mtd/spi-nor/fsl-quadspi.c: In function 'fsl_qspi_read':
  drivers/mtd/spi-nor/fsl-quadspi.c:873:2: warning: format '%d' expects argument of type 'int', but argument 6 has type 'size_t' [-Wformat=]
    dev_dbg(q->dev, "cmd [%x],read from 0x%p, len:%d\n",
    ^

Also drop the '0x' prefixing to the '%p' formatter, since %p already
knows how to format pointers appropriately.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Acked-by: Han xu <han.xu@freescale.com>