usb: gadget: gr_udc: Fix check for invalid number of microframes

The value 0x3 (not 0x11) in the field for additional transaction/microframe
is reserved and should not be let through. Be clear in the error message about
what value caused the error return.

Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>