v3d: Restructure RO allocations using resource_from_handle.

v3d: Restructure RO allocations using resource_from_handle.

I had bugs in the old path where I was laying out as tiled (so we'd render
tiled) but then only allocating space in the shared object for linear
rendering.  The resource_from_handle makes it so the same layout choices
are made in both the import and export scanout cases.  Also, fixes a leak
of the fd that was tripping up the CTS.

Now that we're checking PIPE_BIND_SHARED to choose to use RO, the
DRM_FORMAT_MOD_LINEAR check wasn't needed any more.

Fixes visual corruption and MMU faults in X in renderonly mode.

Fixes: bd09bb1629a7 ("v3d: SHARED but not necessarily SCANOUT buffers on RO must be linear.")