i3c: mipi-i3c-hci-pci: Add support for Multi-Bus Instances

i3c: mipi-i3c-hci-pci: Add support for Multi-Bus Instances

Add support for MIPI I3C Host Controllers with the Multi-Bus Instance
capability.  These controllers can host multiple I3C buses (up to 15)
within a single hardware function (e.g., PCIe B/D/F), providing one
indepedent HCI register set and corresponding I3C bus controller logic
per bus.

Create an MFD cell for each instance and use platform_data to pass the
starting address of the instance's register set.

The MIPI I3C HCI specification defines an Extended Capability that holds
the offset of each instance register set.  Parsing this information is
relatively complex, so include the offsets in driver data for now.

Driver data for additional instances beyond instance 0 will be added in a
subsequent patch.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260106164416.67074-11-adrian.hunter@intel.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>