Pointers to two struct types are used in "ipa_gsi.h", without those
struct types being forward-declared. Add these declarations.
Fixes: c3f398b141a8 ("soc: qcom: ipa: IPA interface to GSI") Signed-off-by: Alex Elder <elder@linaro.org> Signed-off-by: David S. Miller <davem@davemloft.net>