Generalize some qca808x LED functions in preparation for qca807x LED
support.

The LED implementation of qca808x and qca807x is the same but qca807x
supports also Fiber port and have different hw control bits for Fiber
port. To limit code duplication introduce micro functions that takes reg
instead of LED index to tweak all the supported LED modes.
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>