drm/xe: Fix xe_reg_sr.h

Prefer forward declarations over #include xe_reg_sr_types.h

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240513084218.2084-5-michal.wajdeczko@intel.com