s390/boot: remove unused COMPILE_VERSION and ccflags-y

ccflags-y has no effect (no code is built in that directory,
arch/s390/boot/compressed/Makefile defines its own KBUILD_CFLAGS).
Removing ccflags-y together with COMPILE_VERSION.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/boot/Makefile

@@ -3,12 +3,6 @@
 # Makefile for the linux s390-specific parts of the memory manager.
 #
 
-COMPILE_VERSION := __linux_compile_version_id__`hostname |  \
-			tr -c '[0-9A-Za-z]' '_'`__`date | \
-			tr -c '[0-9A-Za-z]' '_'`_t
-
-ccflags-y  := -DCOMPILE_VERSION=$(COMPILE_VERSION) -gstabs -I.
-
 targets := image
 targets += bzImage
 subdir- := compressed