freedreno/a3xx/compiler: ensure min # of cycles after bary instr

freedreno/a3xx/compiler: ensure min # of cycles after bary instr

The results of a bary.f do not appear to be immediatley available, but
there is no explicit sync bit.  Instead the compiler must just ensure
that there are a minimum number of instructions following the bary
before use of the result of the bary.  We aren't clever enough for that
so just throw in some nop's.

Signed-off-by: Rob Clark <robclark@freedesktop.org>