net: ipa: get rid of ipa_cmd_info->direction

The direction field of the ipa_cmd_info structure is set, but never
used.  It seems it might have been used for the DMA_SHARED_MEM
immediate command, but the DIRECTION flag is set based on the value
of the passed-in direction flag there.

Anyway, remove this unused field from the ipa_cmd_info structure.
This is done as a separate patch to make it very obvious that it's
not required.

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