dt: bindings: fix documentation for MARVELL's bt-sd8xxx wireless device

The property marvell,wakeup-pin and marvell,wakeup-gap-ms are read as
u16 in the driver. Fix documentation and example accordingly.

Signed-off-by: Wei-Ning Huang <wnhuang@chromium.org>
Signed-off-by: Rob Herring <robh@kernel.org>