torture: Fix kvm.sh --datestamp regex check

Some versions of grep are happy to interpret a nonsensically placed "-"
within a "[]" pattern as a dash, while others give an error message.
This commit therefore places the "-" at the end of the expression where
it was supposed to be in the first place.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit is contained in:
Paul E. McKenney 2021-02-27 20:55:57 -08:00
commit 114e4a4b48