drm/xe: Rename xe_rtp_regval to xe_rtp_action

It's true that the struct records the register and the value (in form of
2 masks) to restore, but it also records more fields important to
the application of workarounds/tuning, etc. One important part is what
is the macro used to record these fields: SET/CLR/WR/FIELD_SET/etc.

Thinking of the table as a set of rules + actions is more intuitive than
rules + regval.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>