drm/virtio: fix potential integer overflow on shift of a int

drm/virtio: fix potential integer overflow on shift of a int

The left shift of unsigned int 32 bit integer constant 1 is evaluated
using 32 bit arithmetic and then assigned to a signed 64 bit integer.
In the case where i is 32 or more this can lead to an overflow. Fix
this by shifting the value 1ULL instead.

Addresses-Coverity: ("Uninitentional integer overflow")
Fixes: 9bcde7742195 ("drm/virtio: implement context init: handle VIRTGPU_CONTEXT_PARAM_POLL_RINGS_MASK")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20210930101941.16546-1-colin.king@canonical.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>