staging: rtl8192e: Use standard ieee80211 function in rtllib_rx_mgt()

Replace WLAN_FC_GET_STYPE(le16_to_cpu(header->frame_ctl)) and comparison
with standard function to avoid proprietary code and to increase
readability.

Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/26cb0a7758186090a618a134c21e237594bbc525.1694546300.git.philipp.g.hortmann@gmail.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>