ARM: dts: msm: Correct the pet time NS WDOG on msm8937

Timer inaccuracy is within 640ms, so pet time should
be 10s - 640ms = 9360ms.

Change-Id: Ib843f1704766f16bf7a3db0333f592ac95c93c40
Signed-off-by: Maria Yu <aiquny@codeaurora.org>