ASoC: SDCA: support Q7.8 volume format #7950

Job	Run time
Sparse check	3m 38s
GCC static -fanalyzer	4m 30s
GCC build arm64	23m 7s
GCC build i386	17m 25s
GCC build arm64 allmodconfig	2m 15s
Clang build x86_64	5m 8s
GCC build X86_64 with W=1 allmodconfig	2m 8s
GCC build X86_64	24m 28s
GCC build X86_64 with W=1	3m 13s
	1h 25m 52s

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