mtd: remove the dbox2-flash map driver

This driver depends on the CONFIG_DBOX2 symbol which does not exist in
the kernel, which means the driver is dead.

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

diff --cc drivers/mtd/maps/Kconfig
Simple merge

diff --cc drivers/mtd/maps/Makefile
Simple merge

diff --cc drivers/mtd/maps/dbox2-flash.c
Simple merge