i3c: mipi-i3c-hci-pci: Pass base regs as platform data to i3c core device

i3c: mipi-i3c-hci-pci: Pass base regs as platform data to i3c core device

Use the parent's MMIO mapping for multi-bus instances to avoid overlapping
regions.  These instances share the same MMIO address space, but the ranges
are not guaranteed to be contiguous.  By passing base_regs from the parent
mapping, child devices can access their registers without creating
conflicting mappings.

Prepare for multi-bus instance support by passing base_regs to child
devices.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260106164416.67074-9-adrian.hunter@intel.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>