acpi: Fix buffer overflow in do_acpi_dump()

When do_acpi_dump() converts the table name to upper case, pass the
actual size of the output buffer so that the null terminator doesn't get
written beyond the end of the buffer.

Signed-off-by: Andrew Scull <ascull@google.com>
Cc: Simon Glass <sjg@chromium.org>
Cc: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Cc: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/cmd/acpi.c b/cmd/acpi.c
index c543f1e..0e473b4 100644
--- a/cmd/acpi.c
+++ b/cmd/acpi.c
@@ -178,7 +178,7 @@
 		printf("Table name '%s' must be four characters\n", name);
 		return CMD_RET_FAILURE;
 	}
-	str_to_upper(name, sig, -1);
+	str_to_upper(name, sig, ACPI_NAME_LEN);
 	ret = dump_table_name(sig);
 	if (ret) {
 		printf("Table '%.*s' not found\n", ACPI_NAME_LEN, sig);