net: stmmac: Low power management optimization

Do not check for oldlink, always check for phydev link
when we suspend and resume the device.

Change-Id: I9cad2a1ecc3aea62b1b005ba09b3e7f21a07349f
Acked-by: Abhishek Chauhan <abchauha@qti.qualcomm.com>
Signed-off-by: Sunil Paidimarri <hisunil@codeaurora.org>