staging: rtl8188eu: use actual request type as parameter

staging: rtl8188eu: use actual request type as parameter

At the moment, usbctrl_vendorreq's requesttype parameter must be set to 1
for reading and 0 for writing. It's then converted to the actual
bmRequestType for the USB control request. We can simplify the code and
avoid this conversion if the caller passes the actual bmRequestType.

We already have defines for the read and write request types. Move them to
usb_ops_linux.c, they're used only inside this file. Replace the numeric
values with USB constants to make their meaning clearer.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20210406204829.18130-4-martin@kaiser.cx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>