wifi: wilc1000: Increase ASSOC response buffer

In recent access points, information element is longer as they include
additional data which exceeds 256 bytes. To accommodate longer
association response, increase the ASSOC response buffer.

Signed-off-by: Amisha Patel <amisha.patel@microchip.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230509172811.4953-1-amisha.patel@microchip.com