cpputest: fix patch file related build error

The external component was changed to use git am, but one of the patch
files was not updated to the correct format. This made the build fail at
the patching stage.

Fix the patch file and make the build work again.

Signed-off-by: Gyorgy Szing <gyorgy.szing@arm.com>
Change-Id: I6615129eecce23d5d055b4146f6648d451814672
3 files changed