usb: host: remove line for obsolete config USB_HWA_HCD

usb: host: remove line for obsolete config USB_HWA_HCD

Commit 99c8a22f914d ("USB: Move wusbcore and UWB to staging as it is
obsolete") misses to adjust some part in ./drivers/usb/host/Makefile.

Hence, ./scripts/checkkconfigsymbols.py warns:

USB_HWA_HCD
Referencing files: drivers/usb/Makefile

Remove the missing piece of this code removal.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20210818071137.22711-3-lukas.bulwahn@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>