arm64: tegra: Update AHUB clock parent and rate on Tegra234
I2S data sanity tests fail beyond a bit clock frequency of 6.144MHz.
This happens because the AHUB clock rate is too low and it shows
9.83MHz on boot.
The maximum rate of PLLA_OUT0 is 49.152MHz and is used to serve I/O
clocks. It is recommended that AHUB clock operates higher than this.
Thus fix this by using PLLP_OUT0 as parent clock for AHUB instead of
PLLA_OUT0 and fix the rate to 81.6MHz.