avoid the "errp && *errp" pattern (not recommended in "qapi/error.h" comments).
Signed-off-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: NAlistair Francis <alistair.francis@xilinx.com>
Message-Id: <20180208164818.7961-2-f4bug@amsat.org>