This patch adds SPL code for the M28 board. Signed-off-by: Marek Vasut <marek.vasut@gmail.com> Cc: Andy Fleming <afleming@gmail.com> Cc: Stefano Babic <sbabic@denx.de> Cc: Wolfgang Denk <wd@denx.de> Cc: Detlev Zundel <dzu@denx.de>