net/phy: add IC+ IP101A and support APS.

This patch adds the IC+ IP101A Single port 10/100 PHY
and supports the APS (i.e. power saving mode while link is down)
for both IP1001 and IP101A (where this mode is supported).

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>