gst/rtp/: Fix speex (de)payloader. Fixes #358040.

gst/rtp/: Fix speex (de)payloader. Fixes #358040.

Original commit message from CVS:
* gst/rtp/gstrtpspeexdepay.c: (gst_rtp_speex_depay_class_init),
(gst_rtp_speex_depay_get_mode), (gst_rtp_speex_depay_setcaps),
(gst_rtp_speex_depay_process):
* gst/rtp/gstrtpspeexpay.c: (gst_rtp_speex_pay_base_init),
(gst_rtp_speex_pay_class_init), (gst_rtp_speex_pay_setcaps),
(gst_rtp_speex_pay_parse_ident), (gst_rtp_speex_pay_handle_buffer),
(gst_rtp_speex_pay_change_state):
* gst/rtp/gstrtpspeexpay.h:
Fix speex (de)payloader. Fixes #358040.