[MIPS] txx9tmr clockevent/clocksource driver

Convert jmr3927_clock_event_device to more generic
txx9tmr_clock_event_device which supports one-shot mode.  The
txx9tmr_clock_event_device can be used for TX49 too if the cp0 timer
interrupt was not available.

Convert jmr3927_hpt_read to txx9_clocksource driver which does not
depends jiffies anymore.  The txx9_clocksource itself can be used for
TX49, but normally TX49 uses higher precision clocksource_mips.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>