Build: Use Ninja based build

Ninja based build helps to improve build job performance.
A single build-config job takes ~52s for building TF-M.
A Ninja based build takes ~42s.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I956b85bda93f51e0cbef6ea099b1a56e5c2686fd
1 file changed