[Fireworks] modify function for switching digital interface (server side
only)

Patch by Takashi Sakamoto. Here's his mail:

Hi,

This series of patch is for the function to switch digital interface.
AudioFire8A and AudioFirePre8 supports this function.

The current implementation of FFADO for this function is not good in two
points.
1. wrong flag name
2. lack of control

1. According to Echo's owners manual version 2.2, all of models based on
Fireworks have coaxial digital interface. But In
/src/fireworks/efc/efc_cmd.h, there is a flag named as
'EFC_CMD_HW_SPDIF_COAX_SUPPORTED'. This should be indicate 'optical',
not 'coaxial'.

Additionally, I know the actual value of flag for four devices below:
AF2: 0xA1
AF4: 0xE1
AFPre8: 0x625
AF12: 0x11
(special thanks to Doug McLain!)

Only AFPre8 set this flag as 1. So this flag means 'the device has
optical digital interface'.

git-svn-id: svn+ssh://ffado.org/ffado/trunk@2389 2be59082-3212-0410-8809-b0798e1608f0
[Fireworks] Add script to switch digital interface

Script by Takashi Sakamoto.

git-svn-id: svn+ssh://ffado.org/ffado/trunk@2390 2be59082-3212-0410-8809-b0798e1608f0