Revert "ARM: dts: msm: Disable CNSS driver for MSM8996v2"

This reverts commit f2ac3d98 ("ARM: dts: msm: Disable CNSS driver
for MSM8996v2") which disables CNSS driver temporarily due to SMMU issues.
Re-enable CNSS driver in order to have WLAN functionality for MSM8996v2.

Change-Id: Iabd54db0e4cc31d27109cb4be5e14a74d8454910
Signed-off-by: Yue Ma <yuem@codeaurora.org>