goldfish_pipe: don't be clever with #define offsets

It just makes it harder to figure out which commands are being used.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Jin Qian <jinqian@android.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>