net: phy: split devices_in_package

We have two competing requirements for the devices_in_package field.
We want to use it as a bit array indicating which MMDs are present, but
we also want to know if the Clause 22 registers are present.

Since "devices in package" is a term used in the 802.3 specification,
keep this as the as-specified values read from the PHY, and introduce
a new member "mmds_present" to indicate which MMDs are actually
present in the PHY, derived from the "devices in package" value.

Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>