arm/dt: msm8974: add support for SDIO3 on APQ8074

APQ8074 platforms use the SDCC3 as an interface for WiFi adapter.
The device node should be enabled to allow the kernel enumerate
the adapter.

Change-Id: I55a6434c9f66bdeab95b2f0c1e6e971d38d24b5c
Signed-off-by: Ilia Lin <ilialin@codeaurora.org>