ARM: OMAP: re-organize duplicated 32k-timer code

ARM: OMAP: re-organize duplicated 32k-timer code

On OMAP2/3, the gp-timer code can be used for a 32kHz timer simply by
setting the source to be the 32k clock instead of sys_clk.

This patch uses the mach-omap2/timer-gp.c code for 32kHz timer on
OMAP2, moving the logic into mach-omap2/timer-gp.c, and not using
plat-omap/timer32k.c which, for OMAP2, is redundant with the timer-gp
code.

Also, if CONFIG_OMAP_32K_TIMER is enabled, the gptimer-based
clocksource is not used.  Instead the default 32k sync counter is used
as the clocksource (see the clocksource in plat-omap/common.c.)  This
is important for sleep/suspend so there is a valid counter during
sleep.  Note that the suspend/sleep code needs fixing to check for
overflows of this counter.

In addition, the OMAP2/3 details are removed from timer32k.c leaving
that with only OMAP1 specifics.  A follow-up patch will move it from
plat-omap common code to mach-omap1.

Signed-off-by: Kevin Hilman <khilman@mvista.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>