ARM: omap2: fix omap5_realtime_timer_init definition

ARM: omap2: fix omap5_realtime_timer_init definition

There is one more regression introduced by the last build fix:

arch/arm/mach-omap2/timer.c:170:6: error: attribute declaration must precede definition [-Werror,-Wignored-attributes]
void __init omap5_realtime_timer_init(void)
     ^
arch/arm/mach-omap2/common.h:118:20: note: previous definition is here
static inline void omap5_realtime_timer_init(void)
                   ^
arch/arm/mach-omap2/timer.c:170:13: error: redefinition of 'omap5_realtime_timer_init'
void __init omap5_realtime_timer_init(void)
            ^
arch/arm/mach-omap2/common.h:118:20: note: previous definition is here
static inline void omap5_realtime_timer_init(void)

Address this by removing the now obsolete #ifdefs in that file and
just building the entire file based on the flag that controls the
omap5_realtime_timer_init function declaration.

Link: https://lore.kernel.org/r/20200529201701.521933-1-arnd@arndb.de
Fixes: 691f3ba3f60b ("ARM: OMAP2+: Fix regression for using local timer on non-SMP SoCs")
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>