Add support for Axxia DDR retention

Signed-off-by: Calin Copos <calin.copos@windriver.com>
Fix clause 45 MDIO access.

Signed-off-by: Jay Jayatheerthan <jay.jayatheerthan@lsi.com>
Signed-off-by: Calin Copos <calin.copos@windriver.com>
Add NRC access to the config ring

LSI Axxia systems use a config ring to access parts of the hardware.
For various reasons, the config ring access code has been
moved, deleted, etc.  This patch adds ncr access back to ARM platforms.
It also removes invalid accesses to previous methods to access
hardware using the ncr buss.

Signed-off-by: John Jacques <john.jacques@lsi.com>
Signed-off-by: Calin Copos <calin.copos@windriver.com>
LSI_NCR: build fix for the DDR retention

Exposing ncr_register_read and ncr_register_write for the
ddr_retention feature

Signed-off-by: Calin Copos <calin.copos@windriver.com>
AXM55xx: add CPUSET to the default preempt-rt config

Signed-off-by: Calin Copos <calin.copos@windriver.com>