net: ipa: allow arbitrary number of interconnects

Currently we assume that the IPA hardware has exactly three
interconnects.  But that won't be guaranteed for all platforms,
so allow any number of interconnects to be specified in the
configuration data.

For each platform, define an array of interconnect data entries
(still associated with the IPA clock structure), and record the
number of entries initialized in that array.

Loop over all entries in this array when initializing, enabling,
disabling, or tearing down the set of interconnects.

With this change we no longer need the ipa_interconnect_id
enumerated type, so get rid of it.

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