net: mvpp2: rename mis-named "link status" interrupt

The link interrupt is used for way more than just the link status; it
comes from a collection of units to do with the port. The Marvell
documentation describes the interrupt as "GOP port X interrupt".

Since we are adding PTP support, and the PTP interrupt uses this,
rename it to be more inline with the documentation.

This interrupt is also mis-named in the DT binding, but we leave that
alone.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>