net: phy: DP83TC811: Fix disabling interrupts

Fix a bug where INT_STAT1 was written twice and
INT_STAT2 was ignored when disabling interrupts.

Fixes: b753a9fa ("net: phy: DP83TC811: Introduce support for the DP83TC811 phy")
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Dan Murphy <dmurphy@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>