cnss: Set correct boot sequence for WLAN chip

CNSS platform driver should vote for 1.8V IO regulator and 1.8V XTAL
regulator before pulling high WLAN_EN GPIO and emulating PCIe link
for MSM8994.

Change-Id: I5da0f1a35e68826e0b646040f764ce938a89e325
Signed-off-by: Yue Ma <yuem@codeaurora.org>