v3dv: Loosen an assert in copy_buffer_to_image_shader

v3dv: Loosen an assert in copy_buffer_to_image_shader

In f99ac7f2de19 ("v3dv: Don't use color aspects for depth/stencil
images"), we stopped using color aspects for depth/stencil images in a
bunch of cases.  This causes us to trigger an assert in
copy_buffer_to_image_shader where it assumes 16-bit is always color but
now it can also be D16_UNORM.  The assert isn't protecting us from
anything we weren't already doing before so we can just loosen it a bit.

Fixes: f99ac7f2de19 ("v3dv: Don't use color aspects for depth/stencil images")
Reviewed-by: Alejandro Piñeiro <apinheiro@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16592>