3.8: add support for audio amplifier cape

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
3.8: add support for am335x bandgap sensor

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>
3.8: update MPU6050 patches and backport PCA9685 driver

Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>