irq: irqdomain: Change irq_domain_add to detect errors

It should not be valid to add an irq_domain with a logical irq
range that overlaps with another already registered to the
system. Return an error on such an occurrence.

This change also inherently sorts the irq_domains by logical
irq_base as they are added.

Change-Id: Idef697dbe4584d783703d053fbf09f1b17e62ab0
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>