generic: ar8216: skip probe on unused PHY addresses

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@35536 3c298f89-4303-0410-b956-a3cf2f4a3e73
generic: ar8216: add sanity check to ar8216_probe

Verify that the mdio bus has PHY devices with
a supported PHY ID at address 0-4.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@35537 3c298f89-4303-0410-b956-a3cf2f4a3e73
generic: ar8216: don't probe the chip multiple times

It is only needed when the private data is allocated.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>

git-svn-id: svn://svn.openwrt.org/openwrt@35538 3c298f89-4303-0410-b956-a3cf2f4a3e73