sh: remove board_time_init() callback

The only remaining user of board_time_init() is the of-generic
machine, and that just calls the global timer_init() function.
Calling that one has no effect on non-DT platforms, so we can
simply call it unconditionally in place of board_time_init().

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/sh/include/asm/rtc.h

@@ -3,7 +3,6 @@
 #define _ASM_RTC_H
 
 void time_init(void);
-extern void (*board_time_init)(void);
 
 #define RTC_CAP_4_DIGIT_YEAR	(1 << 0)