Can't change CM108 GPIO using ptt_bitnum

[tylerhunt]

Setting the GPIO pin for the CM108 PTT device appears to be broken.

Here's the default configuration:

$> rigctl -L -P CM108 | grep ptt_bitnum -A 2
rig_open: error = (null) No such file or directory 
ptt_bitnum: "Push-To-Talk GPIO bit number"
	Default: 2, Value: 0
	Range: 0.0..7.0, step 1.0

Setting ptt_bitnum shows the configuration option being set:

$> rigctl -L -P CM108 -C ptt_bitnum=3 | grep ptt_bitnum -A 2
rig_open: error = (null) No such file or directory 
ptt_bitnum: "Push-To-Talk GPIO bit number"
	Default: 2, Value: 3
	Range: 0.0..7.0, step 1.0

But when the rig is initialized, the default value is used instead of the configured value:

$> rigctl -L -P CM108 -p /dev/hidraw0 -C ptt_bitnum=3 -vvvv 2>&1 | grep cm108_ptt_set
cm108_ptt_set called
cm108_ptt_set: bit number 2 to state 0
^C