[RISCV] Remove unused HasStdExtZama16b Predicate. NFC

Author: topperc

llvm/lib/Target/RISCV/RISCVFeatures.td

@@ -209,9 +209,6 @@ def HasStdExtAOrZalrsc
 def FeatureStdExtZama16b
     : SubtargetFeature<"zama16b", "HasStdExtZama16b", "true",
                        "'Zama16b' (Atomic 16-byte misaligned loads, stores and AMOs)">;
-def HasStdExtZama16b : Predicate<"Subtarget->hasStdExtZama16b()">,
-                       AssemblerPredicate<(all_of FeatureStdExtZama16b),
-                           "'Zama16b' (Atomic 16-byte misaligned loads, stores and AMOs)">;
 
 def FeatureStdExtZawrs : SubtargetFeature<"zawrs", "HasStdExtZawrs", "true",
                                           "'Zawrs' (Wait on Reservation Set)">;