We no longer need struct gbuf defined in "greybus.h". An upcoming
patch will embed a gbuf struct (not a pointer) into the operation
structure, and to do that we'll need the struct defined prior to the
operation. Just move the gbuf definition into "operation.h".
Signed-off-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>