cxl/core/regs: Add rcd_pcie_cap initialization

Add rcd_pcie_cap and its initialization to cache the offset of cxl1.1
device link status information. By caching it, avoid the walking
memory map area to find the offset when output the register value.

Given that this solution involves port lookups via cxl_pci_find_port()
and multiple exit paths where that reference needs to be dropped,
introduce a new put_cxl_root() scope-based-free handler.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Kobayashi,Daisuke <kobayashi.da-06@fujitsu.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20241002011549.408412-2-kobayashi.da-06@fujitsu.com


Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>