ARM: zynq: DT: Remove bogus value from 'bias-disable' property

In one pinctrl node, a 'bias-disable' property is erroneously assigned a
value.

Fixes: ARM: zynq: DT: Add pinctrl information
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>