fdt: lmb: add reserved regions as no-overwrite

fdt: lmb: add reserved regions as no-overwrite

The boot_fdt_add_mem_rsv_regions() function reserves the memreserve and
reserved-memory regions. These regions are being set with the LMB_NONE
flag which allows overwriting and re-using the regions. This was fine
earlier when the LMB memory map was local and not enforced
globally. But that is no longer the case. Mark these regions as
LMB_NOOVERWRITE so that they cannot be used.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Reported-by: Vaishnav Achath <vaishnav.a@ti.com>