mtd: constify of_device_id array

of_device_id is always used as const.
(See driver.of_match_table and open firmware functions)

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --cc drivers/mtd/devices/docg3.c
Simple merge

diff --cc drivers/mtd/maps/physmap_of.c
Simple merge

diff --cc drivers/mtd/nand/mpc5121_nfc.c
Simple merge

diff --cc drivers/mtd/spi-nor/fsl-quadspi.c
Simple merge