arm: omap2+: select 32k clocksource driver

Now that we have a 32k clocksource driver, let's
select it for OMAP2PLUS builds.
Signed-off-by: NFelipe Balbi <balbi@ti.com>

arch/arm/mach-omap2/Kconfig

@@ -96,6 +96,7 @@ config ARCH_OMAP2PLUS
 	select SOC_BUS
 	select TI_PRIV_EDMA
 	select OMAP_IRQCHIP
+	select CLKSRC_TI_32K
 	help
 	  Systems based on OMAP2, OMAP3, OMAP4 or OMAP5