mfd: da9052-i2c: Staticize da9052_i2c_fix()

da9052_i2c_fix() is only used locally, so let it be static.

Fix the following sparse warning:

drivers/mfd/da9052-i2c.c:63:5: warning: symbol 'da9052_i2c_fix' was not declared. Should it be static?

Cc: Ashish Jangam <ashish.jangam@kpitcummins.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>