mfd: Fix max77693 build failure

Without it we get:

drivers/mfd/max77693.c: In function ‘max77693_i2c_probe’:
drivers/mfd/max77693.c:157:2: error: implicit declaration of function
‘max77693_irq_init’ [-Werror=implicit-function-declaration]
drivers/mfd/max77693.c: In function ‘max77693_resume’:
drivers/mfd/max77693.c:215:2: error: implicit declaration of function
‘max77693_irq_resume’ [-Werror=implicit-function-declaration]
drivers/mfd/max77693-irq.c: In function ‘max77693_irq_lock’:
drivers/mfd/max77693-irq.c:104:2: error: ‘struct max77693_dev’ has no member
named ‘irqlock’
drivers/mfd/max77693-irq.c: In function ‘max77693_irq_sync_unlock’:
drivers/mfd/max77693-irq.c:119:11: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cache’
drivers/mfd/max77693-irq.c:119:42: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cur’
drivers/mfd/max77693-irq.c:122:13: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cur’
drivers/mfd/max77693-irq.c:125:24: error: ‘struct max77693_dev’ has no member
named ‘irqlock’
drivers/mfd/max77693-irq.c: In function ‘max77693_irq_mask’:
drivers/mfd/max77693-irq.c:141:11: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cur’
drivers/mfd/max77693-irq.c:143:11: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cur’
drivers/mfd/max77693-irq.c: In function ‘max77693_irq_unmask’:
drivers/mfd/max77693-irq.c:153:11: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cur’
drivers/mfd/max77693-irq.c:155:11: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cur’
drivers/mfd/max77693-irq.c: In function ‘max77693_irq_thread’:
drivers/mfd/max77693-irq.c:209:26: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cur’
drivers/mfd/max77693-irq.c:211:27: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cur’
drivers/mfd/max77693-irq.c:217:39: error: ‘struct max77693_dev’ has no member
named ‘irq_domain’
drivers/mfd/max77693-irq.c: In function ‘max77693_irq_init’:
drivers/mfd/max77693-irq.c:260:2: error: ‘struct max77693_dev’ has no member
named ‘irqlock’
drivers/mfd/max77693-irq.c:268:12: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cur’
drivers/mfd/max77693-irq.c:269:12: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cache’
drivers/mfd/max77693-irq.c:271:12: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cur’
drivers/mfd/max77693-irq.c:272:12: error: ‘struct max77693_dev’ has no member
named ‘irq_masks_cache’
drivers/mfd/max77693-irq.c:292:10: error: ‘struct max77693_dev’ has no member
named ‘irq_domain’

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>