drm/xe/irq: Clear GFX_MSTR_IRQ as part of IRQ reset

drm/xe/irq: Clear GFX_MSTR_IRQ as part of IRQ reset

Starting with Xe_LP+, GFX_MSTR_IRQ contains status bits that have W1C
behavior. If we do not properly reset them, we would miss delivery of
interrupts if a pending bit is set when enabling IRQs.

As an example, the display part of our probe routine contains paths
where we wait for vblank interrupts. If a display interrupt was already
pending when enabling IRQs, we would time out waiting for the vblank.

That in fact happened recently when modprobing Xe on a Lunar Lake with a
specific configuration; and that's how we found out we were missing this
step in the IRQ enabling logic.

Fix the issue by clearing GFX_MSTR_IRQ as part of the IRQ reset.

v2:
  - Make resetting GFX_MSTR_IRQ be the last step to avoid bit
    re-latching. (Ville)
v3:
  - Swap nesting order: guard loop with the IP version check instead of
    doing the check at each iteration. (Lucas)
v4:
  - Add braces for the "if" statement guarding the loop to make the
    compiler happy. (Gustavo)

BSpec: 50875, 54028, 62357
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20230926221914.106843-2-gustavo.sousa@intel.com
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>