[lldb][AArch64] Simplify AArch64SMEFA64 check

So we only have to read cpuinfo once.

Author: DavidSpickett

lldb/packages/Python/lldbsuite/test/lldbtest.py

@@ -1275,9 +1275,8 @@ def isAArch64SMEFA64(self):
         # smefa64 allows the use of the full A64 instruction set in streaming
         # mode. This is required by certain test programs to setup register
         # state.
-        return self.isAArch64SME() and set(["sme", "smefa64"]).issuperset(
-            set(self.getCPUInfo())
-        )
+        cpuinfo = self.getCPUInfo()
+        return self.isAArch64() and "sme" in cpuinfo and "smefa64" in cpuinfo
 
     def isAArch64MTE(self):
         return self.isAArch64() and "mte" in self.getCPUInfo()