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

This reverts commit b24bd127 which is
commit e0a8c918 upstream.

It breaks the android ABI and if this is needed in the future, can be
brought back in an abi-safe way.

Bug: 161946584
Change-Id: I8e8b822927d0133b8a1ac532ae4dbb9fc7808e10
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>