MLK-12309: mtd: gpmi: workaround for kernel 4.1 NAND boot

MLK-12309: mtd: gpmi: workaround for kernel 4.1 NAND boot

new implementation of GPMI NAND raw access functions was added in kernel
4.1 which changes the way from writing data in mirror mode to writing
data with BCH layout mode.

New implementation can help third party tools to analysis the data since
all data were written in same layout, with or without ECC, but this
implementation doesn't work for NAND boot. Kobs-ng, the tool for NAND
boot will create the boot configuration data for each specific platform
and need to write the data to NAND in mirror mode. In this workaround,
we will keep using the previous raw NAND access function to fix the
issue.

Signed-off-by: Han Xu <han.xu@nxp.com>