clk: at91: check pmc node status before registering syscore ops

clk: at91: check pmc node status before registering syscore ops

BugLink: https://bugs.launchpad.net/bugs/1951822
[ Upstream commit c405f5c15e9f6094f2fa1658e73e56f3058e2122 ]

Currently, at91 pmc driver always register the syscore_ops whatever
the status of the pmc node that has been found. When set as secure
and disabled, the pmc should not be accessed or this will generate
abort exceptions.
To avoid this, add a check on node availability before registering
the syscore operations.

Signed-off-by: Clément Léger <clement.leger@bootlin.com>
Link: https://lore.kernel.org/r/20210913082633.110168-1-clement.leger@bootlin.com
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Fixes: b3b02eac33ed ("clk: at91: Add sama5d2 suspend/resume")
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>