configs: sei510: rework header and fix userdata size

Move android generic config and boot sequence in meson64_android header
and fix size of userdata to use all eMMC on SEI510.

Signed-off-by: Guillaume La Roque <glaroque@baylibre.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
diff --git a/MAINTAINERS b/MAINTAINERS
index bdc998a..a7c355c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -137,6 +137,7 @@
 F:	drivers/power/domain/meson-gx-pwrc-vpu.c
 F:	drivers/video/meson/
 F:	include/configs/meson64.h
+F:	include/configs/meson64_android.h
 N:	meson
 
 ARM BROADCOM BCM283X