[ARM] 5446/1: ohci-at91: Limit vbus_pin assignment to the size of the array

Currently, the vbus_pin assignment loop is limited by the value of the "ports"
variable in the platform data.  Now that the vbus_pin array is no longer
flexible, we can use its actual size.

Signed-off-by: Justin Waters <justin.waters@timesys.com>
Acked-by: Andrew Victor <linux@maxim.org.za>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>