staging: rtl8192e: rename BufferSize to buffer_size in ba_param_set union

Fixes a checkpatch CHECK message.

Signed-off-by: William Durand <will+git@drnd.me>
Link: https://lore.kernel.org/r/20210219101206.18036-5-will+git@drnd.me


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>