group/tf-l3-boot-tests-n1sdp: Add new group and boot test config for N1SDP

Add new group tf-l3-boot-tests-n1sdp.

Add support to fetch the SCP and MCP binaries from the prebuilts
and add boot test config for N1SDP platform in
group/tf-l3-boot-tests-n1sdp.

Also, add this boot test in tf-nomination. This will run the
N1SDP boot test for any change in the n1sdp platform.

Signed-off-by: sahil <sahil@arm.com>
Change-Id: I99f1d1eed5adb1e79fdc6f3b8a04bbe3c0b948ed
3 files changed