static-checks: remove check on modified files

Remove checks on existing files as there is no need to flag warnings on
these. Only in new files should there be a warning when the copyright
year is missing or doesn't match the current year.

Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
Change-Id: Ieea2a6478361377e073f27e343980a3323375ae9
1 file changed