drm/i915/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.

Avoid the potential issue by clearing GFX_MSTR_IRQ as part of the IRQ
reset.

v2:
  - Move logic from gen11_gt_irq_reset() to dg1_irq_reset(). (Matt)

BSpec: 50875, 54028
Cc: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Gustavo Sousa <gustavo.sousa@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230920195351.59421-2-gustavo.sousa@intel.com