linux-imx

MAINTAINERS: remove Dmitry Torokhov's alternate address

I am using gmail.com exclusively and mail.ru was a backup that so far was
not needed. To avoid getting 2 copies of the same message let's drop
mail.ru from MAINTAINERS file.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>