MAINTAINERS: mmp: add Git repository

Add a tree that was set up for to stage the patches for Marvell MMP SoC
support.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>

MAINTAINERS

@@ -10905,6 +10905,7 @@ F:	drivers/media/radio/radio-miropcm20*
 MMP SUPPORT
 R:	Lubomir Rintel <lkundrak@v3.sk>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/lkundrak/linux-mmp.git
 S:	Odd Fixes
 F:	arch/arm/boot/dts/mmp*
 F:	arch/arm/mach-mmp/