s390/mem_detect: provide single get_mem_detect_end

get_mem_detect_end is already used in couple of places with potential
to be utilized in more cases. Provide single get_mem_detect_end
implementation in asm/mem_detect.h to be used by kasan and startup code.

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

arch/s390/include/asm/mem_detect.h

@@ -79,4 +79,16 @@ static inline void get_mem_detect_reserved(unsigned long *start,
 		*size = 0;
 }
 
+static inline unsigned long get_mem_detect_end(void)
+{
+	unsigned long start;
+	unsigned long end;
+
+	if (mem_detect.count) {
+		__get_mem_detect_block(mem_detect.count - 1, &start, &end);
+		return end;
+	}
+	return 0;
+}
+
 #endif