MAINTAINERS: add myself to qemu-char.c

I consider to have enough experience with qemu-char to propose myself as
maintainer. This will allow me to send pull request without waiting for
Paolo.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -1194,6 +1194,7 @@ T: git git://github.com/jnsnow/qemu.git bitmaps
 
 Character device backends
 M: Paolo Bonzini <pbonzini@redhat.com>
+M: Marc-André Lureau <marcandre.lureau@redhat.com>
 S: Maintained
 F: qemu-char.c
 F: backends/msmouse.c