ARM: davinci: Update da8xxevm Maintainers

The e-mail addresses for DA8XXEVM BOARD and DA850_AM18XXEVM BOARD
are invalid.

Remove DA8XXEVM.

Update DA850_AM18XXEVM to have me be the maintainer since I work
for Logic PD and have access to OMAP-L138 and AM1808 EVM kits.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>