vc4: Size transfer temporary mappings appropriately for full maps of 3D.

vc4: Size transfer temporary mappings appropriately for full maps of 3D.

We don't really support reading/writing of 3D textures since the hardware
doesn't do 3D, but we do need to make sure that a pipe_transfer for them
has enough space to store the image.  This was previously not a problem
because the state tracker only mapped a slice at a time until
fb9fe352ea41c7e3633ba2c483c59b73c529845b.  Fixes glean glsl1 tests, which
all have setup of a 3D texture at the start.