USB: EHCI: Safe endianness for transfer buffers after reset in case of HUB with TT

This patch fixes the endianness select for transfer buffers in EHCI
controllers that have Transaction Translator built in the hub.  Also I
cleaned it up to make rid of magic numbers.

Signed-off-by: Vladimir Barinov <vbarinov@ru.mvista.com>
Cc: <david-b@pacbell.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>