Commit 19851c58 (sa1111: allow cascaded IRQs to be used by platforms)
moved the IRQ definitions to the .c file, and added an irq_base member
to the private data structure.

The inerrupt demultiplexer uses irq_base, but the interrupt setup code
does not.  Also, although the commit adds a private data structure to
pass this data, it isn't even referenced, resulting in irq_base being
zero.

We also copied the IRQ numbers from the device info array into the actual
devices, resulting in wrong interrupt numbers passed to the sub-devices.

The net effect of this is that we always overwrite IRQs 0-54, even if
they are allocated elsewhere in the system.

Add the code necessary to setup the private irq_base, and use it in the
IRQ setup code.  Make the SA-1111 probe fail with -EINVAL if there is no
platform data provided.
Acked-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>