ARM: Remove unnecessary selection of TICK_ONESHOT

In 3872c48b (tick: Document TICK_ONESHOT config option) Thomas describes
the circumstances under which TICK_ONESHOT should be selected.  This is
an internal time keeping configuration symbol which should not be
selected by platform or arch code.  So remove our select statements for
it.

This kills these warnings in OMAP builds:

kernel/time/tick-sched.c:47: warning: 'tick_do_update_jiffies64' defined but not used
kernel/time/tick-sched.c:89: warning: 'tick_init_jiffy_update' defined but not used

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>