ARM: OMAP: rx51: fix USB

Commit 10299e2e (ARM: RX-51:
Enable isp1704 power on/off) added power management for isp1704.

However, the transceiver should be powered on by default,
otherwise USB doesn't work at all for networking during
boot.

All kernels after v3.0 are affected.

Cc: stable@kernel.org
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Reviewed-by: Sebastian Reichel <sre@debian.org>
[tony@atomide.com: updated comments]
Signed-off-by: Tony Lindgren <tony@atomide.com>