greybus: fix an allocation flag bug

greybus: fix an allocation flag bug

We allocate message buffers with GFP_KERNEL allocation flags if
possible.  However when an incoming request message is received we
can be in interrupt context, so we must use GFP_ATOMIC in that case.

The computation of gfp_flags in gb_operation_message_init() is
wrong.  It is needlessly using GFP_ATOMIC when allocating outbound
response buffers.  Fix the flawed logic.

Change the name of "data_out" to be "outbound" to be consistent with
usage elsewhere.  (Data/messages are "inbound" or "outbound";
requests are "incoming" or "outgoing".)

Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>