net: ipa: define GSI interrupt types with enums

Define the GSI global interrupt types with an enumerated type whose
values are the bit positions representing the global interrupt types.

Similarly, define the GSI general interrupt types with an enumerated
type whose values are the bit positions of general interrupt types.

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