can: c_can: Add syscon/regmap RAMINIT mechanism

Some TI SoCs like DRA7 have a RAMINIT register specification
different from the other AMxx SoCs and as expected by the
existing driver.

To add more insanity, this register is shared with other
IPs like DSS, PCIe and PWM.

Provides a more generic mechanism to specify the RAMINIT
register location and START/DONE bit position and use the
syscon/regmap framework to access the register.

Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Documentation/devicetree/bindings/net/can/c_can.txt

@@ -12,6 +12,9 @@ Required properties:
 Optional properties:
 - ti,hwmods		: Must be "d_can<n>" or "c_can<n>", n being the
 			  instance number
+- syscon-raminit	: Handle to system control region that contains the
+			  RAMINIT register, register offset to the RAMINIT
+			  register and the CAN instance number (0 offset).
 
 Note: "ti,hwmods" field is used to fetch the base address and irq
 resources from TI, omap hwmod data base during device registration.