dt: bindings: Supply shared ST IRQ defines

These defines are used to allow values used for configuration to be
easily human readable and will lessen the chance of logical mistakes.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lkml.kernel.org/r/1424272444-16230-2-git-send-email-lee.jones@linaro.org


Signed-off-by: Jason Cooper <jason@lakedaemon.net>