ppc/pnv: Introduce a pnv_xive_block_id() helper

ppc/pnv: Introduce a pnv_xive_block_id() helper

When PC_TCTXT_CHIPID_OVERRIDE is configured, the PC_TCTXT_CHIPID field
overrides the hardwired chip ID in the Powerbus operations and for CAM
compares. This is typically used in the one block-per-chip configuration
to associate a unique block id number to each IC of the system.

Simplify the model with a pnv_xive_block_id() helper and remove
'tctx_chipid' which becomes useless.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-Id: <20191125065820.927-19-clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>