drm/vmwgfx: correct fb_fix_screeninfo.line_length

commit aa6de142 upstream.

Previously, the vmwgfx_fb driver would allow users to call FBIOSET_VINFO, but it would not adjust
the FINFO properly, resulting in distorted screen rendering. The patch corrects that behaviour.

See https://bugs.gentoo.org/show_bug.cgi?id=494794 for examples.
Signed-off-by: Christopher Friedt <chrisfriedt@gmail.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
(cherry picked from commit 8dd0cd27)

drivers/gpu/drm/vmwgfx/vmwgfx_fb.c

@@ -179,6 +179,7 @@ static int vmw_fb_set_par(struct fb_info *info)
 		vmw_write(vmw_priv, SVGA_REG_DISPLAY_POSITION_Y, info->var.yoffset);
 		vmw_write(vmw_priv, SVGA_REG_DISPLAY_WIDTH, info->var.xres);
 		vmw_write(vmw_priv, SVGA_REG_DISPLAY_HEIGHT, info->var.yres);
+		vmw_write(vmw_priv, SVGA_REG_BYTES_PER_LINE, info->fix.line_length);
 		vmw_write(vmw_priv, SVGA_REG_DISPLAY_ID, SVGA_ID_INVALID);
 	}