omxil_vout: Generalize and fix the stride/slice height calculations
omxil_vout: Generalize and fix the stride/slice height calculations

On the raspberry pi, the stride is filled in with the right value,
while the slice height is left untouched (and needs to be rounded
up to a multiple of 16).

This fixes rendering of more uncommon resolutions.

Signed-off-by: Martin Storsjö <54669547a225ff20cba8b75a4adca540eef25858@martin.st>

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