Encoder: fixed logical error when vbv-max-bitrate property is not greater than target bitrate.
Encoder: fixed logical error when vbv-max-bitrate property is not greater
than target bitrate.

Maxkbps should remain zero-initialized in this case, not set to
target bitrate.

Signed-off-by: Lim Siew Hoon <e412356d7e67dbdde94e841e5d46937fb9f4e623@intel.com>

rislim/gstreamer-media-SDK,ph0b/gstreamer-media-SDK,ishmael1985/gstreamer-media-SDK,rislim/gstreamer-media-SDK