tc2: Added RSS flash file to the real flash

This change is to place RSS flash file to the flash memory compared to the dummy flash in earlier case.
RSS source code got updated to point to the real flash.

* srec_cat appends RSS flash file after the FIP image.

Signed-off-by: Tintu Thomas <tintu.thomas@arm.com>
Change-Id: I51c5f43a9eabba0c2b6f344204d549b75fed6a73