Rename CONFIG_SYS_TEXT_BASE to CONFIG_TEXT_BASE

The current name is inconsistent with SPL which uses CONFIG_SPL_TEXT_BASE
and this makes it imposible to use CONFIG_VAL().

Rename it to resolve this problem.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/board/qualcomm/dragonboard820c/head.S b/board/qualcomm/dragonboard820c/head.S
index 29be61a..b052a85 100644
--- a/board/qualcomm/dragonboard820c/head.S
+++ b/board/qualcomm/dragonboard820c/head.S
@@ -20,7 +20,7 @@
 _arm64_header:
 	b _start
 	.word 0
-	.quad   CONFIG_SYS_TEXT_BASE-PHYS_SDRAM_1 /* Image load offset, LE */
+	.quad   CONFIG_TEXT_BASE-PHYS_SDRAM_1 /* Image load offset, LE */
 	.quad   0    /* Effective size of kernel image, little-endian */
 	.quad   0    /* kernel flags, little-endian */
 	.quad   0    /* reserved */