greybus: audio: Remove GET_TX/RX_DELAY message types

The 'GB_AUDIO_TYPE_GET_TX_DELAY' and 'GB_AUDIO_TYPE_GET_RX_DELAY'
are no longer a part of the Greybus Audio Device Class Protocol
so remove support for them.  The message numbers are not coalesced
to prevent compatibility issues between the AP and the module.

Testing Done: Played music using a speaker module

Signed-off-by: Mark Greer <mgreer@animalcreek.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>