can: c_can_platform: Fix raminit, use devm_ioremap() instead of devm_ioremap_resource()

The raminit register is shared register for both can0 and can1. Since commit:

    32766ff net: can: Convert to use devm_ioremap_resource

devm_ioremap_resource() is used to map raminit register. When using both
interfaces the mapping for the can1 interface fails, leading to a non
functional can interface.

Signed-off-by: George Cherian <george.cherian@ti.com>
Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Cc: linux-stable <stable@vger.kernel.org> # >= v3.11
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>