mfd: stmpe-i2c: Move .driver structure fields inside {} in stmpe_i2c_driver

Currently, few fields in stmpe_i2c_driver are initialized as:
.driver.owner = THIS_MODULE,

Group them under {}, like:
.driver = {
	.owner = THIS_MODULE,
	...
},

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>