drm/i915/xehp: Check for faults on primary GAM

On Xe_HP the fault registers are now in a multicast register range.
However as part of the GAM these registers follow special rules and we
need only read from the "primary" GAM's instance to get the information
we need.  So a single intel_gt_mcr_read_any() (which will automatically
steer to the primary GAM) is sufficient; we don't need to loop over each
instance of the MCR register.

v2:
 - Update more instances of fault registers.  (Bala)

Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Balasubramani Vivekanandan <balasubramani.vivekanandan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221014230239.1023689-7-matthew.d.roper@intel.com