staging: rtl8188eu: Revert 4 commits breaking ARP

staging: rtl8188eu: Revert 4 commits breaking ARP

commit 66d32fdcbf03851724a8b551d490ae1ddfe6eef2 upstream.

Commit 2ba8444c97b1 ("staging:r8188eu: move IV/ICV trimming into
decrypt() and also place it after rtl88eu_mon_recv_hook()") breaks ARP.

After this commit ssh-ing to a laptop with r8188eu wifi no longer works
if the machine connecting has never communicated with the laptop before.
This is 100% reproducable using "arp -d <ipv4> && ssh <ipv4>" to ssh to
a laptop with r8188eu wifi.

This commit reverts 4 commits in total:

1. Commit 79650ffde38e ("staging:r8188eu: trim IV/ICV fields in
   validate_recv_data_frame()")
This commit depends on 2 of the other commits being reverted.

2. Commit 02b19b4c4920 ("staging:r8188eu: inline unprotect_frame() in
   mon_recv_decrypted_recv()")
The inline code is wrong the un-inlined version contains:
	if (skb->len < hdr_len + iv_len + icv_len)
		return;
	...
Where as the inline-ed code introduced by this commit does:
	if (skb->len < hdr_len + iv_len + icv_len) {
		...
Note the same check, but now to actually continue doing ... instead
of to not do it, so this commit is no good.

3. Commit d86e16da6a5d ("staging:r8188eu: use different mon_recv_decrypted()
   inside rtl88eu_mon_recv_hook() and rtl88eu_mon_xmit_hook().")
This commit introduced a 1:1 copy of a function so that one of the
2 copies can be modified in the 2 commits we're already reverting.

4. Commit 2ba8444c97b1 ("staging:r8188eu: move IV/ICV trimming into
   decrypt() and also place it after rtl88eu_mon_recv_hook()")
This is the commit actually breaking ARP.

Note this commit is a straight-forward squash of the revert of these
4 commits, without any changes.

Cc: Ivan Safonov <insafonov@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>