[MIPS] cevt-txx9: Reset timer counter on initialization

The txx9_tmr_init() will not clear a timer counter register in a certain
case.  The counter register is cleared on 1->0 transition of TCE bit if
CRE=1.  So just clearing the TCE bit is not enough.

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