usb: gadget: remove DUALSPEED from printer

This patch removes the DUALSPEED macro and makes the HS (and FS) case
the default. This is one little step before composite can be used for
descriptor management.

Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Signed-off-by: Felipe Balbi <balbi@ti.com>