baseparse: remove checks for buffer==NULL
baseparse: remove checks for buffer==NULL

Accordifn to docs for GstPadChainFunction buffer cannot be NULL. If we would
leave the check, we would also need more such check below.

cfoch/gstreamer,drothlis/gstreamer,lubosz/gstreamer,ensonic/gstreamer,ylatuya/gstreamer,drothlis/gstreamer,krichter722/gstreamer,Lachann/gstreamer,magcius/gstreamer,lovebug356/gstreamer,jpakkane/gstreamer,ylatuya/gstreamer,cfoch/gstreamer,justinjoy/gstreamer,lovebug356/gstreamer,collects/gstreamer,lubosz/gstreamer,surround-io/gstreamer,cablelabs/gstreamer,lovebug356/gstreamer,jpxiong/gstreamer,drothlis/gstreamer,magcius/gstreamer,centricular/gstreamer,ensonic/gstreamer,mparis/gstreamer,centricular/gstreamer,ylatuya/gstreamer,Distrotech/gstreamer,cfoch/gstreamer,krieger-od/gstreamer,jpxiong/gstreamer,justinjoy/gstreamer,surround-io/gstreamer,Distrotech/gstreamer,shelsonjava/gstreamer,jpxiong/gstreamer,cablelabs/gstreamer,magcius/gstreamer,krichter722/gstreamer,jpakkane/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,cablelabs/gstreamer,jpxiong/gstreamer,ensonic/gstreamer,ensonic/gstreamer,cfoch/gstreamer,cablelabs/gstreamer,StreamUtils/gstreamer,cfoch/gstreamer,magcius/gstreamer,collects/gstreamer,jpakkane/gstreamer,drothlis/gstreamer,centricular/gstreamer,StreamUtils/gstreamer,mparis/gstreamer,lubosz/gstreamer,collects/gstreamer,krieger-od/gstreamer,Distrotech/gstreamer,centricular/gstreamer,StreamUtils/gstreamer,jpakkane/gstreamer,krichter722/gstreamer,shelsonjava/gstreamer,shelsonjava/gstreamer,ahmedammar/platform_external_gst_gstreamer,mparis/gstreamer,lubosz/gstreamer,surround-io/gstreamer,krieger-od/gstreamer,Lachann/gstreamer,lovebug356/gstreamer,collects/gstreamer,centricular/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,shelsonjava/gstreamer,surround-io/gstreamer,surround-io/gstreamer,ahmedammar/platform_external_gst_gstreamer,ahmedammar/platform_external_gst_gstreamer,jpakkane/gstreamer,collects/gstreamer,krieger-od/gstreamer,Distrotech/gstreamer,Lachann/gstreamer,mparis/gstreamer,ensonic/gstreamer,shelsonjava/gstreamer,magcius/gstreamer,lubosz/gstreamer,lovebug356/gstreamer,justinjoy/gstreamer,ahmedammar/platform_external_gst_gstreamer,ylatuya/gstreamer,ylatuya/gstreamer,justinjoy/gstreamer,cablelabs/gstreamer,Lachann/gstreamer,krieger-od/gstreamer,drothlis/gstreamer,Distrotech/gstreamer,mparis/gstreamer,krichter722/gstreamer,ahmedammar/platform_external_gst_gstreamer,justinjoy/gstreamer,krichter722/gstreamer