net: ipa: support COMPILE_TEST

Arrange for the IPA driver to be built when COMPILE_TEST is enabled.

Update the help text to reflect that we support two Qualcomm SoCs.

Suggested-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Alex Elder <elder@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>