staging: r8188eu: rtw_read_port needs no cnt parameter

The cnt parameter in the rtw_read_port function is not used.
Remove it.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20211126173205.21352-2-martin@kaiser.cx


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