config/ast2600: Make position independent

Allows loading one u-boot from another. Useful for testing on hardware.

Reviewed-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Joel Stanley <joel@jms.id.au>
diff --git a/configs/evb-ast2600_defconfig b/configs/evb-ast2600_defconfig
index 3dcbcd2..4788c4f 100644
--- a/configs/evb-ast2600_defconfig
+++ b/configs/evb-ast2600_defconfig
@@ -1,5 +1,6 @@
 CONFIG_ARM=y
 CONFIG_SYS_DCACHE_OFF=y
+CONFIG_POSITION_INDEPENDENT=y
 CONFIG_SPL_SYS_THUMB_BUILD=y
 CONFIG_ARCH_ASPEED=y
 CONFIG_SYS_TEXT_BASE=0x80000000