ramips: fix kmod-sound-mt7620 packaging
Commit
9ff8928bb9c28be701eb963e591afcfd54b9d8c9 renamed the snd-soc-mt7620-i2s
driver and dropped snd-soc-mt7620-wm8960 which selected CONFIG_SND_SOC_WM8960
breaking all ramips builds due to undefined kernel config symbols.
Rework the kmod-sound-mt7620 package to explicitely select the
CONFIG_SND_SOC_WM8960 symbols and change it to bundle the renamed .ko file.
Also remove the @BROKEN flag and exclude it on the rt288x subtarget instead.
Signed-off-by: Jo-Philipp Wich <jo@mein.io>