EINJ, CXL: Fix CXL device SBDF calculation

EINJ, CXL: Fix CXL device SBDF calculation

The SBDF of the target CXL 2.0 compliant root port is required to inject a CXL
protocol error as per ACPI 6.5. The SBDF given has to be in the
following format:

31     24 23    16 15    11 10      8  7        0
+-------------------------------------------------+
| segment |   bus  | device | function | reserved |
+-------------------------------------------------+

The SBDF calculated in cxl_dport_get_sbdf() doesn't account for
the reserved bits currently, causing the wrong SBDF to be used.
Fix said calculation to properly shift the SBDF.

Without this fix, error injection into CXL 2.0 root ports through the
CXL debugfs interface (<debugfs>/cxl) is broken. Injection
through the legacy interface (<debugfs>/apei/einj/) will still work
because the SBDF is manually provided by the user.

Fixes: 12fb28ea6b1cf ("EINJ: Add CXL error type support")
Signed-off-by: Ben Cheatham <Benjamin.Cheatham@amd.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com>
Reviewed-by: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com>
Link: https://patch.msgid.link/20240927163428.366557-1-Benjamin.Cheatham@amd.com
Signed-off-by: Ira Weiny <ira.weiny@intel.com>