arm/dt: msm8974: Disable WCNSS nodes on Dragonboard APQ8074

The Dragonboard APQ8074 doesn't have WCNSS WLAN hardware,
but has QCA6234 WLAN instead. The two WLAN adapters share same MSM GPIOs.
WCNSS driver tries to configure the common GPIOs and causes malfunction
of the QCA6234 hardware.
The WCNSS device tree nodes should be disabled to avoid MSM GPIO
and PMIC configuration by the WCNSS driver.

Change-Id: I3fc60244008a62113e294bc92980a3fd0edd9bec
Signed-off-by: Ilia Lin <ilialin@codeaurora.org>