thermal: int340x: delete bogus length check

This check has a signedness bug and does not work.  If "length" is
larger than "PAGE_SIZE" then "PAGE_SIZE - length" is not negative
but instead it is a large unsigned value.  Fortunately, Takashi Iwai
changed this code to use scnprint() instead of snprintf() so now
"length" is never larger than "PAGE_SIZE - 1" and the check can be
removed.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>