radeonsi: tell the shader disk cache what IR is used

radeonsi: tell the shader disk cache what IR is used

Until 8bef4df196fbb the IR (TGSI or NIR) was used in disk_cache driver_flags.
This commit restores this features to avoid crashing when switching from
one IR to the other.

As radeonsi's default is TGSI, I used "driver_flags & 0x8000000 = 0" for TGSI
to keep the same driver_flags.

Fixes: 8bef4df196f ("radeonsi: add si_debug_options for convenient adding/removing of options")
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Reviewed-by: Marek Olšák <marek.olsak@amd.com>
Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>