arm: socfpga: disable CONFIG_SPL_WDT for gen5 and a10

These boards don't have a watchdog enabled in SPL, so make sure
CONFIG_SPL_WDT is not enabled.

Fixes: commit 6874cb72204f ("watchdog: Split WDT from SPL_WDT")

Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
diff --git a/configs/socfpga_arria10_defconfig b/configs/socfpga_arria10_defconfig
index a2d555b..7cb214d 100644
--- a/configs/socfpga_arria10_defconfig
+++ b/configs/socfpga_arria10_defconfig
@@ -46,3 +46,4 @@
 CONFIG_TIMER=y
 CONFIG_SPL_TIMER=y
 CONFIG_DESIGNWARE_APB_TIMER=y
+# CONFIG_SPL_WDT is not set