staging: r8188eu: remove UsbTxAggDescNum from struct hal_data_8188e

UsbTxAggDescNum in struct hal_data_8188e is set to 0x6 and never
changed. Define this constant and remove UsbTxAggDescNum from the
hal_data_8188e structure.

Signed-off-by: Michael Straube <straube.linux@gmail.com>
Link: https://lore.kernel.org/r/20220201084259.7497-6-straube.linux@gmail.com


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