omap1: Fix sched_clock implementation when both MPU timer and 32K timer are used

Earlier patches select HAVE_SCHED_CLOCK for omaps. To have working sched_clock
also for MPU timer, we need to implement it in a way where the right one gets
selected during the runtime.

Signed-off-by: Tony Lindgren <tony@atomide.com>

diff --git a/arch/arm/plat-omap/include/plat/common.h b/arch/arm/plat-omap/include/plat/common.h
index ef683e0..29b2afb 100644
--- a/arch/arm/plat-omap/include/plat/common.h
+++ b/arch/arm/plat-omap/include/plat/common.h
@@ -37,6 +37,7 @@
 extern struct sys_timer omap_timer;
 extern bool omap_32k_timer_init(void);
 extern int __init omap_init_clocksource_32k(void);
+extern unsigned long long notrace omap_32k_sched_clock(void);
 
 extern void omap_reserve(void);