drm/vmwgfx: Unreserve BO on error

Unlock BOs in reverse order.
Add an acquire context so that lockdep doesn't complain.

Fixes: d6667f0d ("drm/vmwgfx: Fix handling of dumb buffers")
Signed-off-by: Ian Forbes <ian.forbes@broadcom.com>
Signed-off-by: Zack Rusin <zack.rusin@broadcom.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241210195535.2074918-1-ian.forbes@broadcom.com