USB: s3c-hsotg: SoftDisconnect minimum 3ms

The shortest period SoftDisconnect can be asserted for is 3 milliseconds
according to the V210 datasheet, so ensure that we add an msleep() to
the registration code to enforce this.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>