init_config: remove unused local variable 'ret'

Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Don't leak the vdpau_wrapper.cfg file pointer

init_config opens vdpau_wrapper.cfg and reads its contents, but never closes it.
This causes a file descriptor leak if libvdpau is unloaded and reloaded.

Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Reviewed-by: Andy Ritger <aritger@nvidia.com>
Reviewed-by: Josep Torra <josep@fluendo.com>