Yocto: delete libffmpeg-vendor.so file [2/2]

PD#RSP-1869

Problem:
add ffmpeg-vendor code to yocto,delete libffmpeg-vendor.so

Solution:
delete prebuilt libffmpeg-vendor.so
form source build to install libffmpeg-vendor.so

Verify:
S905Y4-AP229+Yocto

Signed-off-by: yanting.zhou <yanting.zhou@amlogic.com>
Change-Id: Id19c738e1faaea9952dfd854e89c9b2fff286c9c