reset: at91: Add reset driver for basic assert/deassert operations

Add support for at91 reset controller's basic assert/deassert
operations. Since this driver conflicts with the
SYSRESET driver because they both bind to the same RSTC node,
implement a custom bind hook that would manually bind the
sysreset driver, if enabled, to the same RSTC DT node.
Furthermore, delete the no longer needed compatibles from the
SYSRESET driver and rename it to make sure than any possible
conflicts are avoided.

Signed-off-by: Sergiu Moga <sergiu.moga@microchip.com>
Tested-by: Mihai Sain <mihai.sain@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>