net: ipa: move endpoint configuration data definitions

Move the definitions of the structures defining endpoint-specific
configuration data out of "ipa_data.h" and into "ipa_endpoint.h".
This is a trivial movement of code without any other change, to
prepare for the next few patches.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>