ARM: 6927/1: SPEAr Clock: Update for single image solution

This patch creates different clk_lookup arrays for individual machines.
These lookup arrays will be registered only if that specific machine is
current machine.

Reviewed-by: Stanley Miao <stanley.miao@windriver.com>
Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>