staging: fsl-mc: update MAINTAINERS

-German has moved on to other things and wished to be
 removed as a maintainer
-cleanup the driver description to use the proper name
 of the driver (i.e. the fsl-mc bus driver) and remove incorrect
 references to Freescale

Signed-off-by: Stuart Yoder <stuart.yoder@nxp.com>
Acked-by: J. German Rivera <German.Rivera@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>