thermal: Add comment explaining test for critical temperature
thermal: Add comment explaining test for critical temperature

The code testing if a temperature should be emulated or not is
not obvious. Add a comment explaining why this test is done.

Signed-off-by: Sascha Hauer <c00cbc2b736c26791a3822db86f8796fe9efff67@pengutronix.de>
Reviewed-by: Mikko Perttunen <4d1e97e91f33be8fb70fd1f552f766fdcea04bd3@nvidia.com>
Signed-off-by: Zhang Rui <f2a4cf793007be8f81a774dc7806c1ffea7b4a2c@intel.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs