v3d: allow TFU blitting for single layer textures
TFU just handles 2D textures.
But for 2D array textures, cubemaps and 3D textures, if only one layer needs to be blitted, then it is like a simple 2D texture, and thus we can also use the TFU.
TFU just handles 2D textures.
But for 2D array textures, cubemaps and 3D textures, if only one layer needs to be blitted, then it is like a simple 2D texture, and thus we can also use the TFU.