ux500: rename MOP board Kconfig

Rename the MOP board Kconfig entries to the same name as the machine
type, so that the machine_is_*() macros work correctly.

Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
[Updated to match changes in the tree]
Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>