gst/law/: Fix capsnego in all four, remove the unused property functions and simplify the chain functions slightly. I...

Original commit message from CVS:
* gst/law/alaw-decode.c: (alawdec_getcaps), (alawdec_link),
(gst_alawdec_base_init), (gst_alawdec_class_init),
(gst_alawdec_init), (gst_alawdec_chain):
* gst/law/alaw-encode.c: (alawenc_getcaps), (alawenc_link),
(gst_alawenc_base_init), (gst_alawenc_class_init),
(gst_alawenc_init), (gst_alawenc_chain):
* gst/law/mulaw-decode.c: (mulawdec_getcaps), (mulawdec_link),
(gst_mulawdec_base_init), (gst_mulawdec_class_init),
(gst_mulawdec_init), (gst_mulawdec_chain):
* gst/law/mulaw-encode.c: (mulawenc_getcaps), (mulawenc_link),
(gst_mulawenc_base_init), (gst_mulawenc_class_init),
(gst_mulawenc_init), (gst_mulawenc_chain):
Fix capsnego in all four, remove the unused property functions and
simplify the chain functions slightly. I guess we could use macros
or something similar for those, since the code is so similar, but
I'm currently too lazy...