efivarfs: Support EFI variable access in 3.10 kernels.
efivarfs: Support EFI variable access in 3.10 kernels.

In the 3.10 kernel, EFI variables are now provided by a dedicated
filesystem that needs to be mounted.

Signed-off-by: Robin H. Johnson <aa3b04a87f185a8b919ce94fe21b810489ffb8d4@gentoo.org>

williamh/openrc,williamh/openrc,dwfreed/openrc,williamh/openrc,OpenRC/openrc,dwfreed/openrc,dwfreed/openrc,OpenRC/openrc,OpenRC/openrc