drm/xe/oa: Don't use hardcoded values

The current implementation uses hardcoded values instead of common defines.

v2:
 - Make the commit a regular commit instead of a fixup commit
 - slightly modify commit message

Signed-off-by: Ohad Sharabi <osharabi@habana.ai>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240721071335.101234-1-osharabi@habana.ai