Optimise ImageMode.getmode

Co-authored-by: Andrew Murray <3112309+radarhere@users.noreply.github.com>

Author: hugovk

src/PIL/ImageMode.py

@@ -42,7 +42,6 @@ def __str__(self) -> str:
 @lru_cache
 def getmode(mode: str) -> ModeDescriptor:
     """Gets a mode descriptor for the given mode."""
-    # if not _modes:
     # initialize mode cache
     endian = "<" if sys.byteorder == "little" else ">"