net: phy: micrel: Allow KSZ8xxx and KSZ90x1 to be used together

net: phy: micrel: Allow KSZ8xxx and KSZ90x1 to be used together

Commit 8eae9b0b45be ("net: phy: micrel: Separate KSZ9000 drivers from
KSZ8000 drivers") separated the KSZ8xxx and KSZ90x1 drivers and warns
that you shouldn't select both of them due to a device ID clash between
the KSZ9021 and the KS8721, asserting that "it is highly unlikely for a
system to contain both a KSZ8000 and a KSZ9000 PHY". Unfortunately
boards like the SAMA5D3xEK do contain both types of PHY, but fortunately
the Linux Micrel PHY driver provides a solution by using different PHY
ID and mask values to distinguish these chips.

This commit contains the following changes:

- The PHY ID and mask values for the KSZ9021 and the KS8721 now match
those used by the Linux driver.
- The warnings about not enabling both drivers have been removed.
- The description for PHY_MICREL_KSZ8XXX has been corrected (these are
10/100 PHYs, not GbE PHYs).
- PHY_MICREL_KSZ9021 and PHY_MICREL_KSZ9031 no longer select PHY_GIGE
since this is selected by PHY_MICREL_KSZ90X1.
- All of the relevant defconfig files have been updated now that
PHY_MICREL_KSZ8XXX does not default to 'Y'.

Signed-off-by: James Byrne <james.byrne@origamienergy.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>