scripts: Add a script to list implemented workarounds

scripts: Add a script to list implemented workarounds

We document the implemented workarounds with

  workaround_name:platforms

with platforms being a comma separated list of 3-letters platform names.

This scripts gather those tags and output a summary of implemented work
arounds. Example usages:

$ ./scripts/list-workarounds ~/gfx/sources/linux-2.6/
WaApplyL3ControlAndL3ChickenMode: hsw, ivb, vlv
WaCatErrorRejectionIssue: hsw, ivb, vlv
WaDisable4x2SubspanOptimization: hsw, ivb
WaDisableBackToBackFlipFix: ivb, vlv
WaDisableDopClockGating: vlv
....

$ ./scripts/list-workarounds ~/gfx/sources/linux-2.6/ -p ivb
WaApplyL3ControlAndL3ChickenMode
WaCatErrorRejectionIssue
WaDisable4x2SubspanOptimization
WaDisableBackToBackFlipFix
WaDisableEarlyCull
...

Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>