mtd: physmap_of: update struct map_info's swap as per map requirement

It is not necessary for all device's maps to be CFI_HOST_ENDIAN.
Maps device can be Big endian or little endian.

Currently it is being taken care using CONFIG_MTD_CFI_LE_BYTE_SWAP or
CONFIG_MTD_CFI_BE_BYTE_SWAP i.e. compile time.

Now update struct map_info's swap field based on device characteristics
defined in device tree.

Signed-off-by: Jagdish Gediya <jagdish.gediya@nxp.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>