n1sdp: remove BL33 copy from n1sdp_system module

BL33 copy by SCP is moved to ARM-TF as part of zeroing out of DDR
memories and ECC enablement. So this patch removes BL33 related
functions from n1sdp_system module.

Change-Id: I1dcdf8a9e6eb9430a0d78da34cc9ad69108be2f3
Signed-off-by: Manoj Kumar <manoj.kumar3@arm.com>