torture: Permit multiple space characters in kvm.sh --kconfig argument

torture: Permit multiple space characters in kvm.sh --kconfig argument

The straightforward way of doing bash substitution for optional strings
leaves a pair of space characters, which the kvm.sh --kconfig option
rejects as ill-formed.  This commit therefore changes the corresponding
regular expression to accommodate more than one space character between
successive Kconfig options.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>