mm-video-v4l2: venc: Set 601-Limited colorspace for color-converted buffers

Colorspace is derived from gralloc-handles for graphic-buffers and set to codec.
RGBA8888 Buffers are converted to YUV via C2D and have 601-Limited color.
When passed to the device-layer, such buffers do not have gralloc-handle
and hence colorspace does not get set.
Set colorspace as 601-L explicitly in such case to the codec.

Bug: 63147656
Bug: 134527014

CRs-Fixed: 2070838
Change-Id: Iae2705b8f4256d8e76309d2d1adb7cb6d3eb1692