gallium/radeon: re-enable unsafe math for graphics shaders

gallium/radeon: re-enable unsafe math for graphics shaders

This reverts commit 4db985a5fa9ea985616a726b1770727309502d81.

The grass no longer disappears, which was the reason the commit was reverted.
This might affect tessellation. We'll see.

Totals from affected shaders:
SGPRS: 151672 -> 150232 (-0.95 %)
VGPRS: 90620 -> 89776 (-0.93 %)
Code Size: 3980472 -> 3920836 (-1.50 %) bytes
LDS: 67 -> 67 (0.00 %) blocks
Scratch: 1357824 -> 1202176 (-11.46 %) bytes per wave

Reviewed-by: Tom Stellard <thomas.stellard@amd.com>