Fix handling of InlineBuffer in root table
Fix handling of InlineBuffer in root table

The handling is suboptimal, as it always loads values out of the spill
table. A future enhancement could handle it more like PushConst so
non-variably-indexed cases can be optimized to use user data sgprs
directly.

GPUOpen-Drivers/llpc,GPUOpen-Drivers/llpc,GPUOpen-Drivers/llpc,GPUOpen-Drivers/llpc,GPUOpen-Drivers/llpc