ARM: OMAP2+: Simplify dmtimer clock aliases

ARM: OMAP2+: Simplify dmtimer clock aliases

The OMAP dmtimer driver allows you to dynamically configure the functional
clock that drives the timer logic. The dmtimer driver uses the device name and
a "con-id" string to search for the appropriate functional clock.

Currently, we define a clock alias for each functional clock source each timer
supports. Some functional clock sources are common to all of the timers on a
device and so for these clock sources we can use a single alias with a unique
con-id string.

The possible functional clock sources for an OMAP device are a 32kHz clock,
a system (MHz range) clock and (for OMAP2 only) an external clock. By defining
a unique con-id name for each of these (timer_32k_ck, timer_sys_ck and
timer_ext_ck) we can eliminate a lot of the clock aliases for timers. This
reduces code, speeds-up searches and clock initialisation time.

Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Acked-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>