Update of MAINTAINERS for RTL8187

As noted by John Linville, the RTL818X maintainers have "moved on", and the
responsibilities for RTL8180 and RTL8187 have been split. This is the
corresponding update of MAINTAINERS.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Acked-by: Herton Ronaldo Krzesinski <herton@mandriva.com.br>
Acked-by: Hin-Tak Leung <htl10@users.sourceforge.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>