net: ipa: move version test inside ipa_endpoint_program_suspend()

IPA version 4.0+ does not support endpoint suspend.  Put a test at
the top of ipa_endpoint_program_suspend() that returns immediately
if suspend is not supported rather than making that check in the caller.

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>