drm/msm/shrinker: Fix can_block() logic

drm/msm/shrinker: Fix can_block() logic

The intention here was to allow blocking if DIRECT_RECLAIM or if called
from kswapd and KSWAPD_RECLAIM is set.

Reported by Claude code review: https://lore.gitlab.freedesktop.org/drm-ai-reviews/review-patch9-20260309151119.290217-10-boris.brezillon@collabora.com/ on a panthor patch which had copied similar logic.

Reported-by: Boris Brezillon <boris.brezillon@collabora.com>
Fixes: 7860d720a84c ("drm/msm: Fix build break with recent mm tree")
Signed-off-by: Rob Clark <robin.clark@oss.qualcomm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Patchwork: https://patchwork.freedesktop.org/patch/714238/
Message-ID: <20260325184106.1259528-1-robin.clark@oss.qualcomm.com>