gstamlvideosink: CB1 add keepLastFrameOnFlush property [1/3]

PD#SWPL-158207

Problem:
add property to set keep last frame when flush.
default is keep last frame,if set to 0,westeros will
clean last frame when flush

Solution:
add property for keep last frame on flush

Verify:
AH212

Signed-off-by: le.han <le.han@amlogic.com>
Change-Id: I94445515136d4a2fd7611f0cc4547a1573b35da3
2 files changed