MAINTAINERS: merge imote2 and stargate

Removed by commit dcd925f9 ("pxa: merge stargate2 and imote2 board
files").

Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Jonathan Cameron <jic23@cam.ac.uk>
Acked-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>