net: ipa: add some new IPA versions

Soon IPA v5.0+ will be supported, and when that happens we will be
able to enable support for the SDX65 (IPA v5.0), SM8450 (IPA v5.1),
and SM8550 (IPA v5.5).

Fix the comment about the GSI version used for IPA v3.1.

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