ugly but working patch to avoid ALSA DMA callback traps on FunKey S

backlight pwm period changed to 40000us to fix high pitch noise issue…

… at 10Khz

back to >0 for checking if using backbuffers in fbtft

back to >0 for checking if using backbuffers in fbtft

Linux 5.9-rc7

Linux 5.9-rc6

Linux 5.9-rc5

Linux 5.9-rc4

Linux 5.9-rc3

Linux 5.9-rc2