mac80211: mwifiex: fix freeze for 60 seconds caused by request_firmware

mac80211: mwifiex: fix freeze for 60 seconds caused by request_firmware

Fix regression in rgpower table loading, caused by using
request_firmware(): when the requested firmware does not exist, e.g.
nxp/rgpower_WW.bin does not exist on OpenWrt builds for WRT3200ACM,
request_firmware() falls back to firmware_fallback_sysfs(), which expects
the firmware to be provided by user space using SYSFS. No such utility is
provided in this configuration, so the entire system locks up for 60
seconds, until the request times out. During this time, no other log
messages are observed, and the device does not respond to commands over
UART.

The request_firmware() call is performed in the following context:
current->comm kworker/1:2  in_task 1  irqs_disabled 0  in_atomic 0

Fixed by using request_firmware_direct(). This prevents fallback to SYSFS,
and avoids delay. The rgpower table is optional. The driver falls back
to the device tree power table if the firmware is not present.

The error code is printed for debugging and returned to the caller,
which only cares for success or failure, so there are no side effects.

Link: #24205
Fixes: #24434
Fixes: https://forum.openwrt.org/t/25-12-0-slow-boot-on-linksys-wrt3200acm/247751
Fixes: https://github.com/torvalds/linux/commit/7b6f16a258065f85793fb2597a290041c1e3d201
Signed-off-by: Georgi Valkov <gvalkov@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/24205
Signed-off-by: Jonas Jelonek <jelonek.jonas@gmail.com>