acpi/apei/erst: Add missing iounmap() on error in erst_exec_move_data()

Add the missing iounmap() before return from erst_exec_move_data()
in the error handling case.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Tony Luck <tony.luck@intel.com>

drivers/acpi/apei/erst.c

@@ -284,8 +284,10 @@ static int erst_exec_move_data(struct apei_exec_context *ctx,
 	if (!src)
 		return -ENOMEM;
 	dst = ioremap(ctx->dst_base + offset, ctx->var2);
-	if (!dst)
+	if (!dst) {
+		iounmap(src);
 		return -ENOMEM;
+	}
 
 	memmove(dst, src, ctx->var2);