Update the rm9200 reset sequence to try executing a board-specific reset
function and move specific board reset to board.
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
introduce serial_exit for this purpose. Use it only when the rm9200
serial driver is active
Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>