Patchsets may change as new commits land. Add logic to
re-apply the updated patchset after a revision bump
without re-cloning the repo. Run `build.sh setup` to
re-apply the patches.

Signed-off-by: John Chung <john.chung@arm.com>
Change-Id: I2d94e1962dc6a44cbbb9ba8a8064526b938cda9c