drm/panthor: Check VMA boundaries for PMD mappings

drm/panthor: Check VMA boundaries for PMD mappings

When checking a different patch[1] sashiko AI pointed out that
panthor needs the same fix[2]:

In the ->huge_fault handler do not install a PMD huge page
mapping if the huge page exceeds the boundaries of the VMA.

[1] https://lore.kernel.org/lkml/20260622215718.1532689-1-lk@c--e.de/
[2] https://sashiko.dev/#/patchset/20260622215718.1532689-1-lk%40c--e.de

Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Fixes: 68cbf96b1e9b ("drm/panthor: Part ways with drm_gem_shmem_object")
Signed-off-by: Christian A. Ehrhardt <lk@c--e.de>
Reviewed-by: Steven Price <steven.price@arm.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/lkml/20260622215718.1532689-1-lk@c--e.de/
Link: https://patch.msgid.link/20260623181942.1536598-1-lk@c--e.de
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>