ARM: 7022/1: allow to detect conflicting zreladdrs

Boards used to specify zreladdr in their Makefile.boot with
zreladdr-y := x, so conflicting zreladdrs were silently overwritten.
This patch changes this to zreladdr-y += x, so that we end
up with multiple words in zreladdr in such a case. We can
detect this later and complain if necessary.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mach-h720x/Makefile.boot b/arch/arm/mach-h720x/Makefile.boot
index 5298401..d875a70 100644
--- a/arch/arm/mach-h720x/Makefile.boot
+++ b/arch/arm/mach-h720x/Makefile.boot
@@ -1,2 +1,2 @@
-   zreladdr-$(CONFIG_ARCH_H720X)	:= 0x40008000
+   zreladdr-$(CONFIG_ARCH_H720X)	+= 0x40008000