MIPS: JZ4740: Set one-shot feature flag for the clockevent

The code for supporting one-shot mode for the clockevent is already there,
only the feature flag was not set.  Setting the one-shot flag allows the
kernel to run in tickless mode.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/2261/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>