arm, davinci: add lowlevel function for dm365 soc

used for booting (for example) from NAND using spl code.

Signed-off-by: Heiko Schocher <hs@denx.de>
Cc: Albert ARIBAUD <albert.u.boot@aribaud.net>
Cc: Sandeep Paulraj <s-paulraj@ti.com>
Cc: Christian Riesch <christian.riesch@omicron.at>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>