drm/i915/gt: Use standard API for seqcount read in TLB invalidation

drm/i915/gt: Use standard API for seqcount read in TLB invalidation

seqprop_sequence() is not intended for use outside seqlock.h.
Although it is accessible as a macro, it is meant to be used only
internally within the header.

Replace it with its proper wrapper, raw_read_seqcount().

Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Co-developed-by: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Christoph Lameter (Ampere) <cl@gentwo.org>
Reviewed-by: Sebastian Brzezinka <sebastian.brzezinka@intel.com>
Link: https://lore.kernel.org/r/20251023132802.654061-1-andi.shyti@linux.intel.com