ARM: mx5: use config to define boot related addresses

Signed-off-by: Richard Zhao <richard.zhao@freescale.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/mach-mx5/Makefile.boot

-   zreladdr-y	:= 0x90008000
-params_phys-y	:= 0x90000100
-initrd_phys-y	:= 0x90800000
+   zreladdr-$(CONFIG_ARCH_MX51)	:= 0x90008000
+params_phys-$(CONFIG_ARCH_MX51)	:= 0x90000100
+initrd_phys-$(CONFIG_ARCH_MX51)	:= 0x90800000