staging: r8188eu: use ieee80211 macro for sequence number

staging: r8188eu: use ieee80211 macro for sequence number

Use the IEEE80211_SEQ_TO_SN macro in function validate_recv_frame to get
the sequence number of an incoming frame.

Map the incoming rx bytes to a struct ieee80211_hdr. Replace the fc
variable with struct ieee80211_hdr's frame control component.

The IEEE80211_SEQ_TO_SN macro takes the sequence control field of an
ieee80211 header and extracts the sequence number. The macro's input
parameter must be in host endianness, the sequence number in the 80211
header is little-endian, we have to convert it to host endianness.

Remove the local GetSequence macro, it is not used any more.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220327180944.712545-9-martin@kaiser.cx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>