net: ipa: configure memory regions early

IPA-resident memory is one of the most primitive resources that
needs initialization, so call init_mem_config() early in
ipa_config().

This is in preparation for initializing the IPA-resident
microcontroller earlier.

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