[AMDGPU][NFC] Remove unused VOP3Mods0Clamp

This is unused and the selection function does not exist.

Reviewed By: foad

Differential Revision: https://reviews.llvm.org/D93188

llvm/lib/Target/AMDGPU/SIInstrInfo.td

@@ -1316,7 +1316,6 @@ def DS128Bit8ByteAligned : ComplexPattern<i64, 3, "SelectDS128Bit8ByteAligned">;
 def MOVRELOffset : ComplexPattern<i32, 2, "SelectMOVRELOffset">;
 
 def VOP3Mods0 : ComplexPattern<untyped, 4, "SelectVOP3Mods0">;
-def VOP3Mods0Clamp : ComplexPattern<untyped, 3, "SelectVOP3Mods0Clamp">;
 def VOP3Mods  : ComplexPattern<untyped, 2, "SelectVOP3Mods">;
 def VOP3NoMods : ComplexPattern<untyped, 1, "SelectVOP3NoMods">;
 // VOP3Mods, but the input source is known to never be NaN.