net: ipa: set IPA v4.11 AP<-modem RX buffer size to 32KB

Increase the receive buffer size used for data received from the
modem to 32KB, to improve download performance by allowing much
greater aggregation.

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