net: ipa: move and redefine ipa_version_valid()

Move the definition of ipa_version_valid(), making it a static
inline function defined together with the enumerated type in
"ipa_version.h".  Define a new count value in the type.

Rename the function to be ipa_version_supported(), and have it
return true only if the IPA version supplied is explicitly supported
by the driver.

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