reset: mchp: sparx5: Fix for lan966x

reset: mchp: sparx5: Fix for lan966x

With the blamed commit it seems that lan966x doesn't seem to boot
anymore when the internal CPU is used.
The reason seems to be the usage of the devm_of_iomap, if we replace
this with devm_ioremap, this seems to fix the issue as we use the same
region also for other devices.

Fixes: 0426a920d6269c ("reset: mchp: sparx5: Map cpu-syscon locally in case of LAN966x")
Reviewed-by: Herve Codina <herve.codina@bootlin.com>
Tested-by: Herve Codina <herve.codina@bootlin.com>
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://lore.kernel.org/r/20250227105502.25125-1-horatiu.vultur@microchip.com
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>