ARM: pxa: hx4700: Initialize DS1WM clock_rate

The asic3 driver now sets the DS1WM clock_rate from the newly added
asic3_platform_data clock_rate field.

This patch initializes the asic3_platform_data clock_rate field on the
hx4700 platform.

Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
Cc: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>