OMAP2+: clockevent: set up GPTIMER clockevent hwmod right before timer init

Set up the GPTIMER hwmod used for the clockevent source immediately
before it is used.  This avoids the need to set up all of the hwmods
until the boot process is further along.  (In general, we want to defer
as much as possible until late in the boot process.)

This second version fixes a bug pointed out by Santosh Shilimkar
<santosh.shilimkar@ti.com>, that would cause the kernel to use an
incorrect timer hwmod name if the selected GPTIMER was not 1 or 12 -
thanks Santosh.  Also, Tarun Kanti DebBarma <tarun.kanti@ti.com>
pointed out that the original patch did not apply cleanly; this has
now been fixed.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Benoît Cousson <b-cousson@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Tarun Kanti DebBarma <tarun.kanti@ti.com>