MFC r347837:
LinuxKPI: Update access_ok macro for v5.0.

Check LINUXKPI_VERSION macro for backwards compatibility.
It's recommended to update any drivers that depend on the older KPI
so we can deprecate < 5.0 code as we update to newer Linux version.
This patch is part of D19565

Reviewed by: hps
Approved by: imp (mentor), hps