Note: This idea is originally from @caveman99 and should be
credited as such. Submitting as a separate PR so the work in
meshtastic/firmware#4148 can be a bit cleaner and Seeed boards
can build while that work is ongoing.
The nrf52 boards that depend on the v7 softdevice all use the same
code and linker files. Rather than duplicate the code, keep it
all together with the platform.
Specify REGULATORY_GAIN and SX126X_MAX_POWER to prevent exceeding regulatory and hardware limits (i.e. overloading the PA input) respectively.
Also update the build flag to define EBYTE_E22_900M30S instead of just EBYTE_E22, since all the builds on the Discourse topic [New 1W DIY variant: Xiao nRF52840 + Ebyte E22-900M30S](https://meshtastic.discourse.group/t/new-1w-diy-variant-xiao-nrf52840-ebyte-e22-900m30s/7904) are using this module.
That should make it clearer as well that the variant header file should be tweaked if DIY builds are using stronger (E22-900M33S, not commonly available at this time) or weaker (E22-900M22S, not popular for DIY builds due to lack of differentiation from ordinary SX1262 modules).
Retain EBYTE_E22 flag alongside EBYTE_E22_900M30S build flag to prevent possible regressions in code paths generally intended for EBYTE E22 modules.
Signed-off-by: Andrew Yong <me@ndoo.sg>
