ipq40xx: qca807x: add SFP improvements

ipq40xx: qca807x: add SFP improvements

Currently, QCA807x doesnt do any kind of validation to see whether it
actually supports the inserted module.

So lets add checks to allow only 1000BaseX and 100BaseFX based modules.

While adding validation, move fiber configuration to insert/remove events
instead of always doing it at config time.
This allows getting rid of the DT property for fiber enable and now only
the upstream sfp phandle is required.

Since we are refactoring fiber related code, lets heavily simplify the
status polling as the current logic is overcomplicated due to previous
wish to support non standard SFP cages that dont have pins properly
connected, that is removed now and only proper SFP cages will work.

Signed-off-by: Robert Marko <robert.marko@sartura.hr>