ath79: fix PLL settings for QCA955x

ath79: fix PLL settings for QCA955x

This adds PLL settings for the ethernet ports of the TP-Link TL-WR1043
v2/v3 and the Openmesh OM5P-AC-v2.

We also change the PLL-settings in the qca9557.dtsi to match the ones
used as default on the ar71xx target.

As of 4b9680f138 those devices have broken ethernet ports as the default
PLL settings defined in the QCA9557.dtsi are applied which are off for
those devices.

Signed-off-by: David Bauer <mail@david-bauer.net>