ARM: U300: bump IRQs to offset 32

The U300 IRQs were bumped once to offset to 1 (in order to avoid
using IRQ 0 which is now NO_IRQ). This was OK as we were still
passing the number of irqs in the .nr_irqs field of the machine,
with descriptors allocated at boot time.

However .nr_irqs should be 0, leading the system to reserve the
first 16 IRQs. Then the VIC driver will complain that IRQs 1
thru 15 are pre-allocated, so to avoid this and use free
descriptors, move all IRQs up to offset 32.

This will all be done away with as we migrate to device tree,
so it is an interim solution.

Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>