cnss2: Support rising edge trigger for WLAN_EN

According to datasheet, it needs to set WLAN_EN pin
to low first and then trigger high before do pcie
enumeration, as for the current code logical it
always assumes the default state of the WLAN_EN is
low, which seems not be appropriate. In particular,
one of our customer has it's own module to set
the default state of the WLAN_EN pin, so it's
hard to guarantee the default state is right.
So in order to make sure it has correct power
sequence with WLAN chipset, adding such fix.

Change-Id: I14030ade506cf0625839b4d7e6ca6b090faa1014
Signed-off-by: Chaoli Zhou <zchaoli@codeaurora.org>