dts: mdm9630: cnss: Migrate to pin control framework

Use pin control framework to control WLAN_EN GPIO for mdm9630.
Also remove GPIO configuration from gpiomux which is not required
any more.

Change-Id: Ib20fae635688005baadca60e771838cef233b9b3
Signed-off-by: Prashanth Bhatta <bhattap@codeaurora.org>