nvidia-driver.eclass: Fix GPU vs version compatibility check

nvidia-driver.eclass: Fix GPU vs version compatibility check

- In commit 245f417b539760ccf4939630f2c6b826ce34a556 I replaced
version_compare() with ver_test but failed to properly adjust the check
from the "is at least" return value to its ver_test equivalent. Invert
the test return value for clarity and check for a version mask less than
PV.
- Use lower case for local variable name.
- Fix a comment while there.

Fixes: https://bugs.gentoo.org/701734
Signed-off-by: Jeroen Roovers <jer@gentoo.org>
Tested-by: Kobboi
Signed-off-by: Jeroen Roovers <jer@gentoo.org>