Improves namedtuple definition (#2501)

I am working on new `mypy` feature and it identified a problem with your `namedtuple` definitions.
python/mypy#11206 (comment)

By standard first string arg should match variable name.

manticore/native/cpu/aarch64.py

@@ -41,7 +41,7 @@ class Aarch64InvalidInstruction(CpuException):
 
 
 # See "C1.2.4 Condition code".
-Condspec = collections.namedtuple("CondSpec", "inverse func")
+Condspec = collections.namedtuple("Condspec", "inverse func")
 COND_MAP = {
     cs.arm64.ARM64_CC_EQ: Condspec(cs.arm64.ARM64_CC_NE, lambda n, z, c, v: z == 1),
     cs.arm64.ARM64_CC_NE: Condspec(cs.arm64.ARM64_CC_EQ, lambda n, z, c, v: z == 0),
@@ -76,7 +76,7 @@ class Aarch64InvalidInstruction(CpuException):
 
 
 class Aarch64RegisterFile(RegisterFile):
-    Regspec = collections.namedtuple("RegSpec", "parent size")
+    Regspec = collections.namedtuple("Regspec", "parent size")
 
     # Register table.
     _table = {}