pitx-imx8m: fix 'video_off' default setting

- When video_off ist set set to 'yes', some initialization routines in
  video_link driver are not executed during u-boot startup sequence.
  As a consequence, linux DP support will fail.
  Set 'video_off=no' to fix this.
Signed-off-by: Thomas Schaefer <thomas.schaefer@kontron.com>

include/configs/pitx-imx8m.h

@@ -161,7 +161,7 @@
 	"fdtfile=pitx-imx8m_hdmi.dtb\0"						\
 	"initrd_addr=0x43800000\0"						\
 	"initrd_high=0xffffffffffffffff\0" 					\
-	"video_off=yes\0"							\
+	"video_off=no\0"							\
 	DISTROBOOT_ENV_SETTINGS							\
 	BOOTENV									\
 	"boot_scripts=boot.scr.uimg boot.scr update_pitx/update.scr\0"