ARM: 7163/2: PL330: Only register usable channels

When the manager is running non-secure, the only channels that can
issue interrupts are the ones that have a 1 in their corresponding bit
in Configuration Register 3. The other ones will generate an abort
when trying to signal the end of the transaction so they are useless
in non-secure mode.

Reference: <1320244259-10496-2-git-send-email-javi.merino@arm.com>

Signed-off-by: Javi Merino <javi.merino@arm.com>
Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>