mtd: nand: marvell: Fix missing memory allocation modifier

The function marvell_nfc_init_dma() allocates a DMA buffer without the
GFP_KERNEL modifier, that triggers this warning:
"marvell_nfc_init_dma() error: no modifiers for allocation."

Fix this by using (GFP_KERNEL | GFP_DMA) instead of only GFP_DMA as the
probe happens in non-interrupt context.

Fixes: 02f26ecf ("mtd: nand: add reworked Marvell NAND controller driver")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Miquel Raynal <miquel.raynal@free-electrons.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>