Update language to comply with Android's inclusive language guidance

See https://source.android.com/setup/contribute/respectful-code for
reference

Lint robot prefer to use inclusive terms for 'sane' as:
https://android-review.googlesource.com/c/platform/system/netd/+/1944696
Replace 'sane' by 'valid'.

BUG=162536543
Test: build, only comment changed

Change-Id: Ieb3124622e8a315a0df18e526bf2067d1d10bb47