media: uapi: Add a pixel format for BGR48 and RGB48

Add BGR48 and RGB48 16-bit per component image formats.

Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

Documentation/userspace-api/media/v4l/pixfmt-rgb.rst

@@ -996,6 +996,60 @@ arranged in little endian order.
 
     \normalsize
 
+16 Bits Per Component
+=====================
+
+These formats store an RGB triplet in six bytes, with 16 bits per component
+stored in memory in little endian byte order. They are named based on the order
+of the RGB components as stored in memory. For instance, RGB48 stores R\
+:sub:`7:0` and R\ :sub:`15:8` in bytes 0 and 1 respectively. This differs from
+the DRM format nomenclature that instead uses the order of components as seen in
+the 48-bits little endian word.
+
+.. raw:: latex
+
+    \small
+
+.. flat-table:: RGB Formats With 16 Bits Per Component
+    :header-rows:  1
+
+    * - Identifier
+      - Code
+      - Byte 0
+      - Byte 1
+      - Byte 2
+      - Byte 3
+      - Byte 4
+      - Byte 5
+
+    * .. _V4L2-PIX-FMT-BGR48:
+
+      - ``V4L2_PIX_FMT_BGR48``
+      - 'BGR6'
+
+      - B\ :sub:`7-0`
+      - B\ :sub:`15-8`
+      - G\ :sub:`7-0`
+      - G\ :sub:`15-8`
+      - R\ :sub:`7-0`
+      - R\ :sub:`15-8`
+
+    * .. _V4L2-PIX-FMT-RGB48:
+
+      - ``V4L2_PIX_FMT_RGB48``
+      - 'RGB6'
+
+      - R\ :sub:`7-0`
+      - R\ :sub:`15-8`
+      - G\ :sub:`7-0`
+      - G\ :sub:`15-8`
+      - B\ :sub:`7-0`
+      - B\ :sub:`15-8`
+
+.. raw:: latex
+
+    \normalsize
+
 Deprecated RGB Formats
 ======================