ARM: shmobile: Use INTCA with sh7372 A3SM power domain

Convert the sh7372 A3SM power domain code to allow
waking up through INTCA and SYSC instead of only
relying on SYSC for wakeups. This allows us to
enter A3SM more or less regardless of the state
of the rest of the system.

Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>