rockchip: rk3399: defconfig: remove SPL raw image support

RK3399 SPL only support FIT image for ATF bl31.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/configs/rock960-rk3399_defconfig b/configs/rock960-rk3399_defconfig
index 7413e4b..abcc53f 100644
--- a/configs/rock960-rk3399_defconfig
+++ b/configs/rock960-rk3399_defconfig
@@ -12,6 +12,7 @@
 # CONFIG_DISPLAY_CPUINFO is not set
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 CONFIG_SPL_TEXT_BASE=0xff8c2000
+# CONFIG_SPL_RAW_IMAGE_SUPPORT is not set
 CONFIG_SPL_STACK_R=y
 CONFIG_SPL_STACK_R_MALLOC_SIMPLE_LEN=0x4000
 CONFIG_SYS_PROMPT="rock960 => "