fat: remove i_version handling from fat_update_time

commit 6bb885ec

 (fat: add functions to update and truncate
timestamps appropriately") added an update_time routine for fat. That
patch added a section for handling the S_VERSION bit, even though FAT
doesn't enable SB_I_VERSION and the S_VERSION bit will never be set when
calling it.

Remove the section for handling S_VERSION since it's effectively dead
code, and will be problematic vs. future changes.

Cc: Frank Sorenson <sorenson@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Frank Sorenson <sorenson@redhat.com>
Message-Id: <20230810-ctime-fat-v1-1-327598fd1de8@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>