iris: Use stream uploader for shader draw parameters.

iris: Use stream uploader for shader draw parameters.

Most vertex data lives in user VBOs in IRIS_MEMZONE_OTHER, which
typically have high bits set to 0xffff.  The shader draw parameters were
being uploaded in IRIS_MEMZONE_DYNAMIC, which have high bets set to 0x2.
This was causing a lot of ping-ponging of high bits, leading to
unnecessary VF cache flushing.

Cuts 7.2% of the flushes in the Civizilation VI demo on Kabylake GT2.