Staging: rtl8192u: Remove unnecessary struct and typedef

This patch removes the _bss_ht struct and the associated type definition
because it is not used and it also introduces the warning:
"WARNING: do not add new typedefs".

Signed-off-by: Cristina Opriceana <cristina.opriceana@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>