Failed to analyze sps from h264 data

[tubzby]

In file "xiecc_rtmp.c", sps nal type is hardcoded as 0x67, it's ok for most of the cases.

Recently I'm working on a DJI remote controller which is android 7.0, it's sps nal byte is 0x27, pps: 0x28, iframe: 0x25, in this case, the sps nal unit is totally ignored thus cause this stream invalid.

We should check if ((byte & 0x1f) == 0x07) to make sure it's a sps unit, which is consistent with other part of xiecc_rtmp.c.