at91sam9rl SoC has an erratum forcing us to toggle the BIAS on USB
suspend/resume events.

This specific handling is only activated when CONFIG_ARCH_AT91SAM9RL is
set and this option is only set when building a non-DT kernel, which is
problematic since non-DT support for at91sam9rl SoC has been removed.

Rework the toggle_bias implementation to attach it to the "at91sam9rl-udc"
compatible string.

Add new compatible strings to avoid executing at91sam9rl erratum handling
on other SoCs.
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>