Enable the --gfxip option in addition to -gfxip
Enable the --gfxip option in addition to -gfxip

The --help option currently shows that the --gfxip option must be used to
select graphics IP version. However, only -gfxip works (single dash).
Using two dashes actually silently uses the default version which is
gfx8. This can be quite annoying for people using amdllpc for the first
time.

GPUOpen-Drivers/llpc,GPUOpen-Drivers/llpc,googlestadia/llpc,GPUOpen-Drivers/llpc,googlestadia/llpc,googlestadia/llpc,googlestadia/llpc,googlestadia/llpc,GPUOpen-Drivers/llpc,GPUOpen-Drivers/llpc