ltq-vdsl-app: extent dsl metrics with state_num and power_state_num

ltq-vdsl-app: extent dsl metrics with state_num and power_state_num

With the old ubus dsl API, the numbers for the individual line_states and
power_states were also returned. These were not ported to the new DSL
C-API. This commit adds the missing information.

For this the internal values are mapped to numbers.

* additional JSON output for state_num:
"state_num": <map_state_number>

Since not all values are meaningful only the following values are
implemented, this can be extended if the future.

* LSTATE_MAP_NOT_INITIALIZED
* LSTATE_MAP_EXCEPTION
* LSTATE_MAP_IDLE
* LSTATE_MAP_SILENT
* LSTATE_MAP_HANDSHAKE
* LSTATE_MAP_FULL_INIT
* LSTATE_MAP_SHOWTIME_NO_SYNC
* LSTATE_MAP_SHOWTIME_TC_SYNC
* LSTATE_MAP_RESYNC

* additinal JSON output for power_level:
"power_state_num": <map_power_satte_number>,

Since there are not so many here, all are mapped.

* PSTATE_MAP_NA,
* PSTATE_MAP_L0,
* PSTATE_MAP_L1,
* PSTATE_MAP_L2,
* PSTATE_MAP_L3,

Signed-off-by: Florian Eckert <fe@dev.tdt.de>
v6:
Add state LSTATE_MAP_NOT_INITILIZED at the beginning of the list
Start the list LSTATE_MAP with -1
Reviewed-by: Andre Heider <a.heider@gmail.com>
(cherry picked from commit 4407d45d9667ab3d376ad4a6b760e07f4dd43e49)