freedreno/a5xx: Remove bogus assertion about BO size.

freedreno/a5xx: Remove bogus assertion about BO size.

The slice->size0 temp is being used as both the array stride (incorrectly)
and as the size of the slice (for this assert).  This assert doesn't seem
to be in the right place to me, if you want to check that offset+slice
size is < bo size, you could just do that at the end of layout setup.

This caused troubles when fixing the temp to be the actual array stride
for filling out the HW state, since then rendering to nonzero levels would
think that the rendering overflowed the BO when it doesn't.

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13668>