drm/xe/xe3p_xpc: Drop stale MCR steering TODO comment

drm/xe/xe3p_xpc: Drop stale MCR steering TODO comment

Proper steering+termination for Xe3p_XPC NODE and BANK multicast ranges
was added in commit 6d5511e56b2d ("drm/xe/xe3p_xpc: Add MCR steering for
NODE and L3BANK ranges") but we forgot to remove the corresponding TODO
comment at the top of the block.  Drop it now to avoid confusion.

Reviewed-by: Shuicheng Lin <shuicheng.lin@intel.com>
Link: https://patch.msgid.link/20260225203719.3310570-2-matthew.d.roper@intel.com
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>