checkpatch: remove obsolete period from "ambiguous SHA1" query

checkpatch: remove obsolete period from "ambiguous SHA1" query

Git dropped the period from its "ambiguous SHA1" error message in commit
0c99171ad2 ("get_short_sha1: mark ambiguity error for translation"), circa
2016.  Drop the period from checkpatch's associated query so as to match
both the old and new error messages.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Sean Christopherson <[email protected]>
Acked-by: Joe Perches <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>