st/va: properly indent buffer.c, config.c, image.c and picture.c

st/va: properly indent buffer.c, config.c, image.c and picture.c

Some lines were using 4 indentation spaces instead of 3.

Signed-off-by: Julien Isorce <j.isorce@samsung.com>
Reviewed-by: Christian K<C3><B6>nig <christian.koenig@amd.com>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>