msm: vidc: add support for enc_chroma_qp_offset

[1] add support for HFI_PROPERTY_PARAM_HEVC_PPS_CB_CR_OFFSET
[2] send (cb_qp_offset << 16 | cr_qp_offset) to firmware
[3] default:0 and overridden: -12
[4] firmware will subtract 12 from driver sent value.
      0 maps to 12 to fw and bitstream has 0
    -12 maps to  0 to fw and bitstream has -12

Change-Id: I286c7088640349691930c95e9b176e4e748c669a
Signed-off-by: Govindaraj Rajagopal <grajagop@codeaurora.org>