ARM: start: fix fdt inside valid memory check

We want to check whether boarddata contains a valid dtb if it's inside
valid memory. This includes the base of SDRAM, so use '>=' instead of '>'.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
commands: of_node fix descripion

Remove copy and paste error

Signed-off-by: Jan Weitzel <j.weitzel@phytec.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>