msm: timer: Remove msm_clocks[] and simplify code

We can simplify the timer code now that we only use the DGT for
the clocksource and the GPT for the clockevent. Get rid of the
msm_clocks[] array and propagate the changes throughout the code.
This reduces the lines of code in this file and improves
readability.
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: David Brown <davidb@codeaurora.org>