v3d: Create separate sampler states for the various blend formats.

v3d: Create separate sampler states for the various blend formats.

The sampler border color is encoded in the TMU's blending format (half
floats, 32-bit floats, or integers) and must be clamped to the format's
range unorm/snorm/int ranges by the driver.  Additionally, the TMU doesn't
know about how we're abusing the swizzle to support BGRA, A, and LA, so we
have to pre-swizzle the border color for those.

We don't really want to spend half a kb on sampler states in most cases,
so skip generating the variants when the border color is unused or is
0,0,0,0.