h265parser: return error for null nalu or slice
h265parser: return error for null nalu or slice

we need return error for any of them is null

Change-Id: Iaae2984bab56be6a1af4092d6b14a60e441064af
Signed-off-by: Xu Guangxin <0f669b203965911dd47bd63faa23578e608c888e@intel.com>

chivakker/libyami,stripes416/libyami,zhaobob/libyami,01org/libyami,uartie/libyami,yizhouwei/libyami,clearlylin/libyami,uartie/libyami,uartie/libyami,yizhouwei/libyami,seanvk/libyami,dspmeng/libyami,stripes416/libyami,01org/libyami,dspmeng/libyami,zhaobob/libyami,01org/libyami,chivakker/libyami,zhaobob/libyami,yizhouwei/libyami,YuJiankang/libyami,lizhong1008/libyami,seanvk/libyami,lizhong1008/libyami,YuJiankang/libyami,YuJiankang/libyami,clearlylin/libyami,stripes416/libyami,dspmeng/libyami,chivakker/libyami,clearlylin/libyami,seanvk/libyami,lizhong1008/libyami