media: vicodec: add documentation to V4L2_CID_FWHT_I/P_FRAME_QP

add documentation to V4L2_CID_FWHT_I/P_FRAME_QP
controls in ext-ctrls-codec.rst

[mchehab+samsung@kernel.org: remove extra blank lines]
Signed-off-by: Dafna Hirschfeld <dafna3@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

Documentation/media/uapi/v4l/ext-ctrls-codec.rst

@@ -1537,6 +1537,14 @@ enum v4l2_mpeg_video_h264_hierarchical_coding_type -
 	non-intra-coded frames, in zigzag scanning order. Only relevant for
 	non-4:2:0 YUV formats.
 
+``V4L2_CID_FWHT_I_FRAME_QP (integer)``
+    Quantization parameter for an I frame for FWHT. Valid range: from 1
+    to 31.
+
+``V4L2_CID_FWHT_P_FRAME_QP (integer)``
+    Quantization parameter for a P frame for FWHT. Valid range: from 1
+    to 31.
+
 MFC 5.1 MPEG Controls
 =====================