[S390] Add support for memory hot-remove.

This patch enables memory hot-remove on s390.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 2ed8812..8d41908 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -317,6 +317,9 @@
 	def_bool y
 	depends on SPARSEMEM
 
+config ARCH_ENABLE_MEMORY_HOTREMOVE
+	def_bool y
+
 source "mm/Kconfig"
 
 comment "I/O subsystem configuration"