wifi: wilc1000: fix for absent RSN capabilities WFA testcase

Mandatory WFA testcase
CT_Security_WPA2Personal_STA_RSNEBoundsVerification-AbsentRSNCap,
performs bounds verfication on Beacon and/or Probe response frames. It
failed and observed the reason to be absence of cipher suite and AKM
suite in RSN information. To fix this, enable the RSN flag before extracting RSN
capabilities.

Fixes: cd21d99e ("wifi: wilc1000: validate pairwise and authentication suite offsets")
Signed-off-by: Amisha Patel <amisha.patel@microchip.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230421181005.4865-1-amisha.patel@microchip.com