Revert "net: phy: mscc: macsec: reject PN update requests"

This reverts commit a698195f which is
commit e0a8c918 upstream.

It breaks the Android ABI so revert it for now, if it is needed in the
future, it can be brought back in an ABI-safe way.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I8176a4f67c346aa762721515bd797078581eef1b