image: fdt: check "status" of "/reserved-memory" subnodes

image: fdt: check "status" of "/reserved-memory" subnodes

boot_fdt_add_mem_rsv_regions() scans the subnodes of
"/reserved-memory" and adds them to reserved lmb regions.
Currently this scanning does not take into "status" property.
Even if the subnode is disabled, it gets added to the
reserved lmb regions.

This patch checks the "status" property before adding it
to reserved lmb regions.

Signed-off-by: Thirupathaiah Annapureddy <thiruan@linux.microsoft.com>