mips: ath79: clock:- Unmap region obtained by of_iomap

Free memory mapping, if ath79_clocks_init_dt_ng is not successful.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
Fixes: 3bdf1071 ("MIPS: ath79: update devicetree clock support for AR9132")
Cc: antonynpavlov@gmail.com
Cc: albeu@free.fr
Cc: hackpascal@gmail.com
Cc: sboyd@codeaurora.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14915/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>