arm: mvebu: x530: Don't build mkeficapsule

The x530 board doesn't use EFI and our toolchains don't include gnutls
so disable the tool in the defconfig.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/configs/x530_defconfig b/configs/x530_defconfig
index 89612be..a5b1cc3 100644
--- a/configs/x530_defconfig
+++ b/configs/x530_defconfig
@@ -95,3 +95,4 @@
 CONFIG_WDT=y
 CONFIG_WDT_ORION=y
 CONFIG_SPL_TINY_MEMSET=y
+# CONFIG_TOOLS_MKEFICAPSULE is not set