hevc_enc: update the attributes for vaConfig creating
hevc_enc: update the attributes for vaConfig creating

For media studio libva, It's necessary to pass two attribute:
VAConfigAttribRTFormat and VAConfigAttribRateControl to libva;
The value of VAConfigAttribRateControl should be VA_RC_MB|VA_RC_CBR
instead of RATE_CONTROL_CBR;
Or else, HEVC encoding will end up with an error: attribute not supported.

Signed-off-by: dongping wu <eada3ae4a96a673269eca90300aaefadacf3db15@intel.com>

01org/libyami,01org/libyami,YuJiankang/libyami,YuJiankang/libyami,YuJiankang/libyami,01org/libyami