wifi: rtl8xxxu: Fix memory leaks with RTL8723BU, RTL8192EU

In the Linux kernel, the following vulnerability has been resolved:

wifi: rtl8xxxu: Fix memory leaks with RTL8723BU, RTL8192EU

The wifi + bluetooth combo chip RTL8723BU can leak memory (especially?)
when it's connected to a bluetooth audio device. The busy bluetooth
traffic generates lots of C2H (card to host) messages, which are not
freed correctly.

To fix this, move the dev_kfree_skb() call in rtl8xxxu_c2hcmd_callback()
inside the loop where skb_dequeue() is called.

The RTL8192EU leaks memory because the C2H messages are added to the
queue and left there forever. (This was fine in the past because it
probably wasn't sending any C2H messages until commit e542e66b7c2e
("wifi: rtl8xxxu: gen2: Turn on the rate control"). Since that commit
it sends a C2H message when the TX rate changes.)

To fix this, delete the check for rf_paths > 1 and the goto. Let the
function process the C2H messages from RTL8192EU like the ones from
the other chips.

Theoretically the RTL8188FU could also leak like RTL8723BU, but it
most likely doesn't send C2H messages frequently enough.

This change was tested with RTL8723BU by Erhard F. I tested it with
RTL8188FU and RTL8192EU.