usb: musb: Fix hub port setting for SPLIT transactions

The ifdef'ed Linux kernel code uses the 1 based port number, whereas U-Boot
puts a 0 based port number into the register. The reason the 0 based port
number apparently works can probably be taken from the USB 2.0 spec:

8.4.2.2 Start-Split Transaction Token
... The host must correctly set the port field for single and multiple TT
hub implementations. A single TT hub implementation *may ignore* the port
field.

Actually, as far as I understand, a multi TT hub defaults to single TT
(bAlternateSetting: 0) until switched via SetInterface, so even "port 42"
would work.

The change was verified by hardcoding the port number to a wrong value,
SPLIT transactions kept working (although using a DWC2 instead of MUSB).
Tested hubs are the RPi onboard SMC9514 and an external "05e3:0608
Genesys Logic, Inc. USB-2.0 4-Port HUB". The former is a multi TT hub,
the latter single TT only.

Addendum: Tested on sunxi/MUSB by Hans de Goede

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>

drivers/usb/musb-new/musb_host.c

@@ -2098,7 +2098,7 @@ int musb_urb_enqueue(
 							       &hubaddr,
 							       &portnr);
 				qh->h_addr_reg = hubaddr;
-				qh->h_port_reg = portnr - 1;
+				qh->h_port_reg = portnr;
 			}
 #endif
 		}