drm/fourcc: Add 32b float formats

Add 1, 2, 3, and 4 component 32b float formats, so that buffers with
these formats can be imported/exported with fourcc+modifier, and/or
created by gbm.

These correspond to PIPE_FORMAT_{R32,R32G32,R32G32B32,R32G32B32A32}_FLOAT
in mesa.

v2: Fix comment describing float32 layout [Sima]

Signed-off-by: Rob Clark <[e-mail]>
Acked-by: Simona Vetter <[e-mail]>
Acked-by: Daniel Stone <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Baryshkov <[e-mail]>

include/uapi/drm/drm_fourcc.h

···
 #define DRM_FORMAT_BGR161616F    fourcc_code('B', 'G', 'R', 'H') /* [47:0] B:G:R 16:16:16 little endian */
 
 /*
+ * Floating point - 32b/component
+ * IEEE 754-2008 binary32 float
+ * [31:0] sign:exponent:mantissa 1:8:23
+ */
+#define DRM_FORMAT_R32F          fourcc_code('R', ' ', ' ', 'F') /* [31:0] R 32 little endian */
+#define DRM_FORMAT_GR3232F       fourcc_code('G', 'R', ' ', 'F') /* [63:0] R:G 32:32 little endian */
+#define DRM_FORMAT_BGR323232F    fourcc_code('B', 'G', 'R', 'F') /* [95:0] R:G:B 32:32:32 little endian */
+#define DRM_FORMAT_ABGR32323232F fourcc_code('A', 'B', '8', 'F') /* [127:0] R:G:B:A 32:32:32:32 little endian */
+
+/*
  * RGBA format with 10-bit components packed in 64-bit per pixel, with 6 bits
  * of unused padding per component:
  */