pata_arasan: Initialize cf clock to 166MHz

PATA arasan driver expects the clock to be set to 166 MHz for proper
functioning.  This patch sets clk to 166 MHz in probe.

Signed-off-by: Vipul Kumar Samar <vipulkumar.samar@st.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>