mtd: nand: Arasan: Add subpage configuration support

mtd: nand: Arasan: Add subpage configuration support

Add support for disabling subpage write support via
CONFIG_SYS_NAND_NO_SUBPAGE_WRITE.

Currently the Linux Arasan driver does not support subpage writes and in
case of running UBI and accessing the same UBI volume from both U-Boot
and Linux it is required to have the same subpage write configuration
else the location of the UBI headers (EC + VID) will be misaligned
(subpage vs page) and incompatible. Hence the need for disabling
subpage write support in the U-Boot Arasan NAND driver.

Signed-off-by: Martin Lund <malu@gomspace.com>
Acked-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>