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-mxs/Makefile.boot b/arch/arm/mach-mxs/Makefile.boot
index eb541e0..07b11fe 100644
--- a/arch/arm/mach-mxs/Makefile.boot
+++ b/arch/arm/mach-mxs/Makefile.boot
@@ -1 +1 @@
-zreladdr-y := 0x40008000
+zreladdr-y += 0x40008000