drm/i915/dsc: add the PPS number to the register content macros

Improve clarity by specifying the PPS number in the register content
macros. It's easier to notice if macros are being used for the wrong
register.

Cc: Suraj Kandpal <suraj.kandpal@intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Suraj Kandpal <suraj.kandpal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/58de57b04ad2da5207f52c56c9e40663aaf16173.1693933849.git.jani.nikula@intel.com