MAINTAINERS: add Masahiro Yamada as a Kbuild maintainer

It has been difficult lately for Michal to work on Kbuild on his
regular basis.  We discussed the maintainership of Kbuild, and I
decided to be a co-maintainer.

Add myself to the maintainer field, and replace the repository with
my own.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Michal Marek <mmarek@suse.com>

MAINTAINERS

@@ -7084,9 +7084,9 @@ S:	Maintained
 F:	fs/autofs4/
 
 KERNEL BUILD + files below scripts/ (unless maintained elsewhere)
+M:	Masahiro Yamada <yamada.masahiro@socionext.com>
 M:	Michal Marek <mmarek@suse.com>
-T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild.git for-next
-T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild.git rc-fixes
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git
 L:	linux-kbuild@vger.kernel.org
 S:	Maintained
 F:	Documentation/kbuild/