remoteproc: imx_rproc: use devm_ioremap

remoteproc: imx_rproc: use devm_ioremap

We might need to map an region multiple times, becaue the region might
be shared between remote processors, such i.MX8QM with dual M4 cores.
So use devm_ioremap, not devm_ioremap_resource.

Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Richard Zhu <hongxing.zhu@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/1615029865-23312-7-git-send-email-peng.fan@oss.nxp.com
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>