mach-snapdragon: of_fixup: set dr_mode for RB1/2 boards

mach-snapdragon: of_fixup: set dr_mode for RB1/2 boards

The RB1 and RB2 have a single USB controller which is manually muxed
between a type-c port and an internal USB hub via a DIP switch. OTG is
supported in Linux, but the DWC3 driver in U-Boot can only handle a
single mode, and defaults to peripheral mode.

We did hack around this on the RB2, but the RB1 got left out.

Now that we can fix up the live tree before devices are bound, drop the
DTS hacks and do the fixup at runtime instead.

Reviewed-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Tested-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>