staging: rtl8188eu: Add device id for MERCUSYS MW150US v2

This device was added to the stand-alone driver on github.
Add it to the staging driver as well.

Link: https://github.com/lwfinger/rtl8188eu/commit/2141f244c3e7
Signed-off-by: Michael Straube <straube.linux@gmail.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200312093652.13918-1-straube.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>