Platform: Corstone-1000: Increase BL1_1 code size to 48 KiB

In preparation for some refactoring of the existing BL1_1
code stage of TF-M.

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: I876cb830acac500a8421314d44612824f4942103
1 file changed