net: ipa: drop an error message

There is no need for gsi_modem_channel_halt() to report an error,
because gsi_generic_command() will already have done that if the
command times out.  So get rid of the extra message.

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