soc: imx: imx8m-blk-ctrl: off by one in imx8m_blk_ctrl_xlate()

The > comparison should be >= to prevent reading one element beyond the
end of the array.  The onecell_data->domains[] array is allocated in
imx8m_blk_ctrl_probe() and it has "onecell_data->num_domains" elements.

Fixes: 5b340e7813d4 ("soc: imx: add i.MX8M blk-ctrl driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>