ARM: zImage: don't define unused symbol initrd_phys

The only user of initrd_phys is arch/arm/boot/bootp/init.S which still
gets the value passed to.
Acked-by: Eric Miao <eric.miao@canonical.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

arch/arm/boot/compressed/Makefile

@@ -79,16 +79,13 @@ endif
 EXTRA_CFLAGS  := -fpic -fno-builtin
 EXTRA_AFLAGS  := -Wa,-march=all
 
-# Supply ZRELADDR, INITRD_PHYS and PARAMS_PHYS to the decompressor via
-# linker symbols.  We only define initrd_phys and params_phys if the
-# machine class defined the corresponding makefile variable.
+# Supply ZRELADDR and PARAMS_PHYS to the decompressor via linker symbols.  We
+# only define params_phys if the machine class defined the corresponding
+# makefile variable.
 LDFLAGS_vmlinux := --defsym zreladdr=$(ZRELADDR)
 ifeq ($(CONFIG_CPU_ENDIAN_BE8),y)
 LDFLAGS_vmlinux += --be8
 endif
-ifneq ($(INITRD_PHYS),)
-LDFLAGS_vmlinux += --defsym initrd_phys=$(INITRD_PHYS)
-endif
 ifneq ($(PARAMS_PHYS),)
 LDFLAGS_vmlinux += --defsym params_phys=$(PARAMS_PHYS)
 endif