usb: host: ohci-pxa27x: use of_property_read_bool()

for checking if a property is present or not,
of_property_read_bool is more appropriate than of_get_property()

Signed-off-by: Saurabh Sengar <saurabh.truth@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>