net: ipa: move definition of enum ipa_irq_id

Move the definition of the ipa_irq_id enumerated type out of
"ipa_interrupt.h" and into "ipa_reg.h", and flesh out its set of
defined values.  Each interrupt id indicates a particular type of
IPA interrupt that can be signaled.  Their numeric values define bit
positions in the IPA_IRQ_* registers, so should their definitions
should accompany the definition of those register offsets.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>