MFC r296902:

MFC r296902:
Improve detection of extended QSFP diagnostics.

The standards in the QSFP diagnostics area are not clear when the
additional measurements are present or not. Use a valid temperature
reading as an indicator for the presence of voltage and TX/RX power
measurements.

Sponsored by:	Mellanox Technologies
Tested by:	Netflix
Differential Revision:	https://reviews.freebsd.org/D5391
Reviewed by:	gallatin

git-svn-id: svn://svn.freebsd.org/base/stable/10@297640 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f