Affected all unified targets as USE_VTX_RTC6705 must be defined to allow supporting that VTX option. Would cause the low power index settings for RTC6705 to override the settings for other VTX type and set the vtxtable power level index to 2 instead of 1.
Moved vtxtable frequency mode implementation into `vtx_common.c`.
This makes the implementation available for all vtx types and allows
for some code deduplication (see point below)
Removed band and channel tracking from tramp and rtc6705.
The hardware underlying both only support frequency mode and
the tracking is now done in `vtx_common.c` using the new factory flag.
Deleted vtxStringXXX. to continue supporting builds without
`USE_VTX_TABLE`, new infrastructure was created in
`drivers/vtx_table.c`, which loads fixed tables into vtxTableXXX
when built witout `USE_VTX_TABLE`. Individual vtx implementations no
longer need to load any band/channel tables. They only need to load
their individual power tables when built without `USE_VTX_TABLE`.
Additionally this allows for the next point:
Fully integrated vtxTableXXX and removed the old and no longer needed
indirection of frequency and power tables in `vtxDevice_t`.
Removed VTX_SETTINGS_* constants from `vtx_common.h` and replaced them
with the vtxtable equivalent.
rtc6705 implementation now uses power values from vtxtable instead of
using indices directly. It also stops using index 0. This makes it
consistent with other vtx implementations and is more user configurable.
It also cleans up `telemetry\srxl.c` which had to have a special case for rtc6705.
Finally, frequency entries in the vtxtable can now be marked as empty
by setting their frequency to 0. Betaflight will never allow a blocked
channel to be selected. This is useful for vtxtable index mode
(FACTORY flag set) where manufacturer-defined bands can be truncated
to ensure compliance with local laws and regulations.
