cpufreq: armada-8k: add ap807 support

Add support for the Armada AP807 die to armada-8k. This uses a
different compatible for the CPU clock which needs to be added to
the cpufreq driver.

This commit takes a different approach to the WindRiver patch
"cpufreq: armada: enable ap807-cpu-clk" in that rather than calling
of_find_compatible_node() for each compatible, we use a table of
IDs instead.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>