ext2: mark as deprecated

Add a DEPRECATED keyword to the kernel parameter description,
to warn users that this filesystem doesn't support dates beyond 2038.

Signed-off-by: Michael Opdenacker <michael.opdenacker@bootlin.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20240222095001.137660-1-michael.opdenacker@bootlin.com>