drm/xe: free madvise VMA array on L2 flush failure

drm/xe: free madvise VMA array on L2 flush failure

xe_vm_madvise_ioctl() allocates madvise_range.vmas in get_vmas().
After get_vmas() succeeds with at least one VMA, error paths must go
through free_vmas so the array is released before the madvise details are
destroyed.

The L2 flush validation path added for PAT madvise rejects some
SVM/userptr ranges after get_vmas() has succeeded, but jumps directly to
madv_fini. This skips kfree(madvise_range.vmas), leaking the VMA array on
each failed ioctl.

Jump to free_vmas instead, matching the other validation failure paths
after get_vmas() has succeeded.

Fixes: 4f39a194d41e ("drm/xe/xe3p_lpg: Restrict UAPI to enable L2 flush optimization")
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patch.msgid.link/20260708073422.725186-1-lgs201920130244@gmail.com
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
(cherry picked from commit c3a1c3579b1250060da73507a4acef712974c78a)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>