bus: imx-weim: Take the 'status' property value into account

Currently we have an incorrect behaviour when multiple devices
are present under the weim node. For example:

&weim {
	...
	status = "okay";

	sram@0,0 {
		...
        	status = "okay";
	};

	mram@0,0 {
		...
        	status = "disabled";
    	};
};

In this case only the 'sram' device should be probed and not 'mram'.

However what happens currently is that the status variable is ignored,
causing the 'sram' device to be disabled and 'mram' to be enabled.

Change the weim_parse_dt() function to use
for_each_available_child_of_node()so that the devices marked with
'status = disabled' are not probed.

Cc: <stable@vger.kernel.org>
Suggested-by: Wolfgang Netbal <wolfgang.netbal@sigmatek.at>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Olof Johansson <olof@lixom.net>