s390/sclp: release SCLP early buffer after kernel initialization

The SCLP early buffer is used only during kernel initialization and can be
freed afterwards. The only way to ensure that it is not released while
being in use, is to release it in free_initmem().
Acked-by: NHeiko Carstens <hca@linux.ibm.com>
Reviewed-by: NAlexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: NAlexander Egorenkov <egorenar@linux.ibm.com>
[agordeev@linux.ibm.com: added debug output]
Signed-off-by: NAlexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: NHeiko Carstens <hca@linux.ibm.com>

arch/s390/mm/init.c

@@ -215,6 +215,9 @@ void free_initmem(void)
 	__set_memory((unsigned long)_sinittext,
 		     (unsigned long)(_einittext - _sinittext) >> PAGE_SHIFT,
 		     SET_MEMORY_RW | SET_MEMORY_NX);
+	free_reserved_area(sclp_early_sccb,
+			   sclp_early_sccb + EXT_SCCB_READ_SCP,
+			   POISON_FREE_INITMEM, "unused early sccb");
 	free_initmem_default(POISON_FREE_INITMEM);
 }