clk/qcom: implement clk dump

Add support for dumping a few of the clocks used on Qualcomm platforms.
Naming the Global PLL's, Root Clock Generators, and gate clocks.

This helps a lot with platform bringup and feature enablement by making
it easy to sanity check that the clocks are programmed correctly.

== Usage ==

Enable CONFIG_CMD_CLK and "#define LOG_DEBUG" at the top of
qcom-<soc>.c.

The "clk dump" command should print the states of all the gates, GPLLs
and RCGs for your SoC.

== Glossary ==

RCG: Root Clock Generator
* Takes in some fairly arbitrary high freq clock (configurable clock
source and options for taking just even pulses and other things)
* Output frequency = input_freq * (m/n) * (1/d) where m/n are arbitrary
8 or 16-bit values (depending on the RCG), and d is a number (with
support for .5 offsets).

GPLL: Global Phase Locked Loop
* Crystal as input
* integer multiplier + exponent part (2^-40)

Gate: Simple on/off clock
* Put between RCGs and the peripherals they power
* Required to allow for correct power sequencing

If you do the maths manually using the equations from "clk dump", the
numbers should roughly line up by they're likely to be out by a handful
of MHz. They output is formatted so that it can be pasted directly into
the python interpreter.

Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>

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