module: Remove outdated comment about text_size

The text_size bit referred to by the comment has been removed as of commit

  ac3b4328 ("module: replace module_layout with module_memory")

and is thus no longer relevant. Remove it and comment about the contents of
the masks array instead.

Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20250429113242.998312-23-vschneid@redhat.com


Signed-off-by: Petr Pavlu <petr.pavlu@suse.com>