cpufreq: Add a cpufreq driver for Marvell Dove

The Marvell Dove SoC can run the CPU at two frequencies. The high
frequencey is from a PLL, while the lower is the same as the DDR
clock. Add a cpufreq driver to swap between these frequences.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---
Sort header files
Remove unneeded header files.
Notify only on change
Use get_cpu_device(0), devm_clk_get()
Use platform_get_resource_byname()
Error check clk_prepare_enable()
mvebu: Dove: Instantiate cpufreq driver.

Add a platform driver definition to instantiate the dove cpufreq
driver. Also indicate the ARCH has cpufreq support, so allowing the
cpufreq framework to be enabled.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
---
Make resource names consistent.
Fix length of ranges
mvebu: Dove: Enable cpufreq driver in defconfig

Add cpufreq to dove_defconfig, so it is built by default.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
mvebu: Dove: Add clocks and DFS interrupt to cpu node in DT.

The dove-cpufreq driver needs access to the DDR and CPU clock.  There
is also an interrupt generated when the DFS hardware completes a
change of frequencey. Add these to the cpu node in DT.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>