mfd: Fix max8925 irq control bit incorrect setting

In max8925_irq_sync_unlock(), irq control bit is set at the same time.
Zero means enabling irq, and one means disabling irq.

The original code is:
	irq_chg[0] &= irq_data->enable;

It should be changed to:
	irq_chg[0] &= ~irq_data->enable;

Otherwise, irq control bit is mess.

Signed-off-by: Kevin Liu <kliu5@marvell.com>
Signed-off-by: Haojian Zhuang <haojian.zhuang@marvell.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>