luks: remove superfluous _mapper_dev (#3031)

archinstall/lib/luks.py

@@ -19,9 +19,6 @@ class Luks2:
 	key_file: Path | None = None
 	auto_unmount: bool = False
 
-	# will be set internally after unlocking the device
-	_mapper_dev: Path | None = None
-
 	@property
 	def mapper_dev(self) -> Path | None:
 		if self.mapper_name:
@@ -172,8 +169,6 @@ class Luks2:
 			debug(f"Closing crypt device {child.name}")
 			SysCommand(f"cryptsetup close {child.name}")
 
-		self._mapper_dev = None
-
 	def create_keyfile(self, target_path: Path, override: bool = False) -> None:
 		"""
 		Routine to create keyfiles, so it can be moved elsewhere