net: ipa: move the definition of gsi_ee_id

Move the definition of the gsi_ee_id enumerated type out of "gsi.h"
and into "ipa_version.h".  That latter header file isolates the
definition of the ipa_version enumerated type, allowing it to be
included in both IPA and GSI code.  We have the same requirement for
gsi_ee_id, and moving it here makes it easier to get only that
definition without everything else defined in "gsi.h".

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