staging: rtl8192u: ieee80211: Remove typedef to the tx_pending_t structure

Using typedef for a structure type is not suggested in Linux kernel coding
style guidelines. So remove typedef from structure tx_pending_t.
The typedef name is not used anywhere. All variables of this type are declared
using "struct tx_pending_t".
Also change the structure name to tx_pending since it is normally only
typedefs that have names that end in _t.

Signed-off-by: sayli karnik <karniksayli1995@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>