greybus: remove unused function descriptor fields and change class->function_type

Greybus spec was updated to remove a number of unused function descriptor
fields. In addition, the class field was change to function_type to avoid
confusion with the concept of high-level class drivers.

Signed-off-by: Matt Porter <mporter@linaro.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
greybus: update string descriptor length field to __u8 type to match spec

Greybus spec was updated to make the length field a single byte. Update
the type and remove endian handling of that field in the core.

Signed-off-by: Matt Porter <mporter@linaro.org>
Reviewed-by: Alex Elder <elder@linaro.org>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>
greybus: update descriptor type enums to match renumbering in spec

Greybus spec updated the descriptor type values and added an
additional class descriptor type. Change the enum accordingly.

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