Kconfig: move NXP specific stuff into a sub-menu

Having NXP specific items in the main menu is confusing. Especially
the comment line

   *** Other functionality shared between NXP SoCs ***

is simply misleading.

Move all NXP stuff into a separate sub-menu.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
1 file changed