shader/arithmetic: Implement FCMP immediate + register variant

Trivially add the encoding for this.

src/video_core/engines/shader_bytecode.h

@@ -1893,6 +1893,7 @@ public:
         ICMP_IMM,
         FCMP_RR,
         FCMP_RC,
+        FCMP_IMMR,
         MUFU,  // Multi-Function Operator
         RRO_C, // Range Reduction Operator
         RRO_R,
@@ -2205,6 +2206,7 @@ private:
             INST("0111110-0-------", Id::HSET2_IMM, Type::HalfSet, "HSET2_IMM"),
             INST("010110111010----", Id::FCMP_RR, Type::Arithmetic, "FCMP_RR"),
             INST("010010111010----", Id::FCMP_RC, Type::Arithmetic, "FCMP_RC"),
+            INST("0011011-1010----", Id::FCMP_IMMR, Type::Arithmetic, "FCMP_IMMR"),
             INST("0101000010000---", Id::MUFU, Type::Arithmetic, "MUFU"),
             INST("0100110010010---", Id::RRO_C, Type::Arithmetic, "RRO_C"),
             INST("0101110010010---", Id::RRO_R, Type::Arithmetic, "RRO_R"),

src/video_core/shader/decode/arithmetic.cpp

@@ -137,7 +137,8 @@ u32 ShaderIR::DecodeArithmetic(NodeBlock& bb, u32 pc) {
         break;
     }
     case OpCode::Id::FCMP_RR:
-    case OpCode::Id::FCMP_RC: {
+    case OpCode::Id::FCMP_RC:
+    case OpCode::Id::FCMP_IMMR: {
         UNIMPLEMENTED_IF(instr.fcmp.ftz == 0);
         Node op_c = GetRegister(instr.gpr39);
         Node comp = GetPredicateComparisonFloat(instr.fcmp.cond, std::move(op_c), Immediate(0.0f));