ARM: dts: msm: add PCIe AUX clk freq for sa6155, sa8155, sa8195

Replace deprecated PCIe DT entry for PCIe AUX clock controller
setting with the correct entry and value. PCIe core controller
requires AUX clock to be 19.2MHz.

Change-Id: Ia670d8e75f75939c2798d795e21771402d83569c