thermal/debugfs: Allow tze_seq_show() to print statistics for invalid trips

Commit a6258fde ("thermal/debugfs: Make tze_seq_show() skip invalid
trips and trips with no stats") modified tze_seq_show() to skip invalid
trips, but it overlooked the fact that a trip may become invalid during
a mitigation eposide involving it, in which case its statistics should
still be reported.

For this reason, remove the invalid trip temperature check from the
main loop in tze_seq_show().

The trips that have never been valid will still be skipped after this
change because there are no statistics to report for them.

Fixes: a6258fde ("thermal/debugfs: Make tze_seq_show() skip invalid trips and trips with no stats")
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>