* xduoo x3ii/x20: Better line out support
* less granular volume settings (too many steps before)
* Better handling of swiching sample rates
* Log actual sample rate in debug menu
Most credit goes to Roman Stolyarov
Additional integration [re]work by myself
Change-Id: I63af3740678cf2ed3170f61534e1029c81826bb6
Provided by Roman Stolyarov
Integration, Refactoring, and Upstreaming by Solomon Peachy
X3II confirmed working by forum tester, X20 is nearly identical.
This includes bootloader, main firmware, and the flash image patcher.
Eventual Todo:
* Further refactor AGPTek Rocker & xduoo hiby bootloaders
* Further refactor AGPTek Rocker & xduoo hosted platform code
Change-Id: I34a674051d368efcc75d1d18c725971fe46c3eee