r600: fix sin,cos functions on r600

r600: fix sin,cos functions on r600

r600 doesnt need the same normalization as r700 - instead it requires
range to be truncated to -pi..pi

I left the range trunc also effective on r700 althouch according the docs
it has sufficent range (-512*PI, +512*PI). The instructions seem
to be used not too often to cause perf loss because of this

Based on patches and testing by Conn Clark and Alain Perrot