mtd: maps: add const qualifiers

Be a bit stricter and add few more 'const' qualifiers.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

diff --cc drivers/mtd/maps/bfin-async-flash.c
Simple merge

diff --cc drivers/mtd/maps/dc21285.c
Simple merge

diff --cc drivers/mtd/maps/gpio-addr-flash.c
Simple merge

diff --cc drivers/mtd/maps/impa7.c
Simple merge

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

diff --cc drivers/mtd/maps/ixp4xx.c
Simple merge

diff --cc drivers/mtd/maps/lantiq-flash.c
Simple merge

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

diff --cc drivers/mtd/maps/pxa2xx-flash.c
Simple merge

diff --cc drivers/mtd/maps/rbtx4939-flash.c
Simple merge

diff --cc drivers/mtd/maps/sa1100-flash.c
Simple merge

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

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