net: stmmac: Add support for PHY interrupts

Driver only supported polling mode. Add PHY interrupt support.

Change-Id: Icfd4986c5e71ccbc6e10b76553a08c86cbdee05d
Acked-by: Nagarjuna Chaganti <nchagant@qti.qualcomm.com>
Signed-off-by: Suraj Jaiswal <jsuraj@codeaurora.org>