dca: set output buffer size correctly (fixes #6509, fixes #7459)
dca: set output buffer size correctly (fixes #6509, fixes #7459)

Some filters and outputs rely on the samples count (which was correct),
others on the bytes size (which was not), accounting for why decoding
failed only in some combinations.

vlc-mirror/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.1,jomanmuk/vlc-2.2,vlc-mirror/vlc,xkfz007/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc,jomanmuk/vlc-2.2,krichter722/vlc,shyamalschandra/vlc,vlc-mirror/vlc-2.1,vlc-mirror/vlc-2.1,shyamalschandra/vlc,jomanmuk/vlc-2.2,vlc-mirror/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,krichter722/vlc,shyamalschandra/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.2,vlc-mirror/vlc,jomanmuk/vlc-2.1,xkfz007/vlc,xkfz007/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc,vlc-mirror/vlc,vlc-mirror/vlc-2.1,jomanmuk/vlc-2.2,xkfz007/vlc,shyamalschandra/vlc,krichter722/vlc,vlc-mirror/vlc-2.1,xkfz007/vlc,vlc-mirror/vlc-2.1,krichter722/vlc,jomanmuk/vlc-2.1,vlc-mirror/vlc,krichter722/vlc,shyamalschandra/vlc,jomanmuk/vlc-2.2,shyamalschandra/vlc,xkfz007/vlc,krichter722/vlc,xkfz007/vlc,jomanmuk/vlc-2.1,krichter722/vlc