cnss: Set the default state of WLAN_EN GPIO to low

Change the default state of WLAN_EN GPIO from high to low. It will be
pulled high when CNSS platform driver probes and PCIe enumeration has
to be started after it by CNSS platform driver, otherwise WLAN chip
cannot be enabled correctly.

Change-Id: I9c665b50a4494422035cde80f9d392de5ce1a143
Signed-off-by: Yue Ma <yuem@codeaurora.org>