sh: allow clocksource drivers to register sched_clock backends

There is no arch-specific sched_clock implementation for sh, resulting
in use of the old default jiffies-based implementation. Instead, use
the modern generic sched_clock framework so that drivers can register
better backends.
Signed-off-by: Rich Felker <dalias@libc.org>

arch/sh/Kconfig

@@ -38,6 +38,7 @@ config SUPERH
 	select GENERIC_IDLE_POLL_SETUP
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_CMOS_UPDATE if SH_SH03 || SH_DREAMCAST
+	select GENERIC_SCHED_CLOCK
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
 	select HAVE_MOD_ARCH_SPECIFIC if DWARF_UNWINDER