MAINTAINERS: update entries affecting VIA Technologies

Since the original maintainer-Joseph Chan (josephchan@via.com.tw) doesn't
handle the Linux driver for VIA now, I would like to request to update the
maintainer for the SD/MMC CARD CONTROLLER DRIVER and VIA
UNICHROME(PRO)/CHROME9 FRAMEBUFFER DRIVER before we find a better one.

Signed-off-by: Bruce Chang <brucechang@via.com.tw>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: Joseph Chan <JosephChan@via.com.tw>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Harald Welte <HaraldWelte@viatech.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>