ppc/pnv: Subclass quad xscom callbacks

Make the existing pnv_quad_xscom_read/write be P9 specific, in
preparation for a different P10 callback.

Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
Reviewed-by: Frederic Barrat <fbarrat@linux.ibm.com>
Message-ID: <20230704054204.168547-3-joel@jms.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
3 files changed