drm/framebuffer: Use actual bpp for DRM_IOCTL_MODE_GETFB

When userspace queries the properties of a frame buffer, the number of
bits per pixel is derived from the deprecated drm_format_info.cpp[]
field, which does not take into account block sizes.

Fix this by using the actual number of bits per pixel instead.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/b612780feef200b7f914a674db28ed227e7cdc64.1657294931.git.geert@linux-m68k.org

drivers/gpu/drm/drm_framebuffer.c

@@ -530,7 +530,7 @@ int drm_mode_getfb(struct drm_device *dev,
 	r->height = fb->height;
 	r->width = fb->width;
 	r->depth = fb->format->depth;
-	r->bpp = fb->format->cpp[0] * 8;
+	r->bpp = drm_format_info_bpp(fb->format, 0);
 	r->pitch = fb->pitches[0];
 
 	/* GET_FB() is an unprivileged ioctl so we must not return a