ARC: HSDK: Fix CPU frequency value

CPU on HSDK board runs at 500MHz after preloader so fix
wrong CPU frequency value in hsdk_defconfig.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
diff --git a/configs/hsdk_defconfig b/configs/hsdk_defconfig
index 37f6190..844deca 100644
--- a/configs/hsdk_defconfig
+++ b/configs/hsdk_defconfig
@@ -2,7 +2,7 @@
 CONFIG_ISA_ARCV2=y
 CONFIG_TARGET_HSDK=y
 CONFIG_SYS_TEXT_BASE=0x81000000
-CONFIG_SYS_CLK_FREQ=1000000000
+CONFIG_SYS_CLK_FREQ=500000000
 CONFIG_DEFAULT_DEVICE_TREE="hsdk"
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200n8"