etnaviv: reduce rs alignment requirement for two pixel pipes GPU

etnaviv: reduce rs alignment requirement for two pixel pipes GPU

The rs alignment doesn't have to be multiplied by # of pixel pipes.

This works on GC2000 which doesn't have the SINGLE_BUFFER feature.

This fixes some cubemaps (NPOT / small mipmap levels) because aligning by 8
breaks the expected alignment of 4 for tiled format. We don't want to mess
with the alignment of tiled formats.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Reviewed-by: Christian Gmeiner <christian.gmeiner@gmail.com>