rpi sound cards: Fix Codec Zero rate switching

The Raspberry Pi Codec Zero (and IQaudIO Codec) don't notify the DA7213
codec when it needs to change PLL frequencies. As a result, audio can
be played at the wrong rate - play a 48kHz sound immediately after a
44.1kHz sound to see the effect, but in some configurations the codec
can lock into the wrong state and always get some rates wrong.

Add the necessary notification to fix the issue.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>