ARM: ep93xx: fix missing-prototype warnings

ARM: ep93xx: fix missing-prototype warnings

ep93xx_clocksource_read() is only called from the file it is declared in,
while ep93xx_timer_init() is declared in a header that is not included here.

arch/arm/mach-ep93xx/timer-ep93xx.c:120:13: error: no previous prototype for 'ep93xx_timer_init'
arch/arm/mach-ep93xx/timer-ep93xx.c:63:5: error: no previous prototype for 'ep93xx_clocksource_read'

Fixes: 000bc17817bf ("ARM: ep93xx: switch to GENERIC_CLOCKEVENTS")
Acked-by: Alexander Sverdlin <alexander.sverdlin@gmail.com>
Link: https://lore.kernel.org/r/20230516153109.514251-3-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>