firmware: Handle overlapping load and link addresses in relocation

This patch extends relocation to handle overlapping load and link
addresses.

The updated relocation will work fine in most cases except when the
relocate copy loop itself falls in overlapping load and link addresses.

Signed-off-by: Xiang W <wxjstz@126.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>