wifi_hal: Fix access check of control param file

Currently, the driver control param file is created write-only,
so fix the check:

https://android.googlesource.com/kernel/msm-modules/qcacld/+/refs/heads/android-msm-coral-4.14-android11-qpr1/core/hdd/src/wlan_hdd_main.c#190



More importantly the open below uses O_WRONLY as only a write is
necessary, there is no need to check for read access.
Otherwise, WiFi fails to be enabled:

WifiHAL : Failed to access driver state control param Permission denied, 13 at /sys/kernel/boot_wlan/boot_wlan

Fixes: 8996467b ("wifihal: Update driver control param to check driver is ready")
Test: Manual build and functionality test
Signed-off-by: Pablo Mendez Hernandez <pablomh@gmail.com>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Change-Id: If6308cd790c69d2d57815ef6815c779258005eff