GSI register definitions for IPA v5.5 are the same as those used for
IPA v5.0.

Update ipa_reg_id_valid() to reflect that IPA v5.0+ supports source
and destination resource groups 4 through 7.

Add the definitions of IPA register offsets and fields for IPA v5.5.
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>