Remove unconditional if condition
Remove unconditional if condition

Now that we link with spvgen statically, comparing any spvgen pointers
to null is redundant.

This fixes an internal clang build warning-as-error.

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