MAINTAINERS: update Cortina/Gemini patterns

MAINTAINERS: update Cortina/Gemini patterns

Commit 4d5ae32f5e1e ("net: ethernet: Add a driver for Gemini gigabit
ethernet") added invalid patterns.  Fix it.

Link: http://lkml.kernel.org/r/65b104609e0071d0fbe0dcce3a8e6138a4cf8c25.1517147485.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Hans Ulli Kroll <ulli.kroll@googlemail.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>