torture: Check for "Call trace:" as well as "Call Trace:"

Different architectures capitalize their splats differently.  Who knew?

This commit therefore checks for both arm64 "Call trace:" and x86
"Call Trace:".

Reported-by: Joel Fernandes <joelagnelf@nvidia.com>
Closes: https://lore.kernel.org/all/553c33d8-2b51-4772-8aef-97b0163bc78e@nvidia.com/


Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com>