mtd: maps: Get rid of the latch-addr-flash driver

Looks like this driver was initially added to support the NOR on the
DA830-EVM (Davinci) board, but the board file update was never merged.

Keeping unused drivers just adds to the maintenance burden, so let's
remove it if nobody uses it.

Cc: David Griego <dgriego@mvista.com>
Cc: Aleksey Makarov <amakarov@ru.mvista.com>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: Savinay Dharmappa <savinay.dharmappa@ti.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
Acked-by: Sekhar Nori <nsekhar@ti.com>