libvideorender: CB1 fix crash on executeCmd [1/1]

PD#TV-111307

Problem:
when DTV changes channel fast, sometimes
popen return null, it causes fget crash with null point

Solution:
invoking fget after popen success

Verify:
AH212

Change-Id: I56fac937c337c5666f3f02982ab25f28f7d39ad8
Signed-off-by: fei.deng <fei.deng@amlogic.com>
1 file changed