tegra2: Add support for Ventana

Ventana is a board which is very similar to Seaboard. Support it by
re-using board/nvidia/seaboard/seaboard.c with minor run-time conditionals.

v5: Makefile: Use cmd_link_o_target, remove unused clean/distclean targets.
v6: Make gpio_config_uart_seaboard() static.
v7: Add MAINTAINERS entry for Ventana. Tom Warren doesn't have Ventana, so
    he asked me to add myself for this board.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/boards.cfg b/boards.cfg
index 12f5f6f..b831515 100644
--- a/boards.cfg
+++ b/boards.cfg
@@ -207,6 +207,7 @@
 smdkv310		     arm	 armv7	     smdkv310		 samsung	s5pc2xx
 harmony                      arm         armv7       harmony             nvidia         tegra2
 seaboard                     arm         armv7       seaboard            nvidia         tegra2
+ventana                      arm         armv7       ventana             nvidia         tegra2
 u8500_href                   arm         armv7       u8500               st-ericsson    u8500
 actux1_4_16                  arm         ixp         actux1              -              -           actux1:FLASH2X2
 actux1_8_16                  arm         ixp         actux1              -              -           actux1:FLASH1X8