wifi: wilc1000: set preamble size to auto as default in wilc_init_fw_config()

wifi: wilc1000: set preamble size to auto as default in wilc_init_fw_config()

WILC driver currently applies some default configuration whenever the firmware
is initialized, and sets the default preamble size to short. However, despite
this passed option, firmware is also able to successfully connect to access
points only using long preamble, so this setting does not really enforce short
preambles and is misleading regarding applied configuration.

Update default configuration and make it match the firmware behavior by passing
the existing WILC_FW_PREAMBLE_AUTO value (2 instead of 0). The updated setting
does not really alter firmware behavior since it is still capable to connect to
both short preamble and long preamble access points, but at list the setting now
expresses for real the corresponding firmware behavior.

More info: it has been implemented to address the transmission (Tx) blackout
issue observed in the 802.11b mode. The modification has no impact on the other
modes, which will continue to work as they did in the previous implementation.
This change will allow the 802.11b transmission (2, 5.5, 11Mbps) to use long
preamble.

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Signed-off-by: Alexis Lothoré <alexis.lothore@bootlin.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://msgid.link/20240115-wilc_1000_fixes-v1-1-54d29463a738@bootlin.com