Fix following compilation error when enabling CONFIG_TWL4030_BCI_BATTERY

drivers/power/twl4030_bci_battery.c: In function 'twl4030_bci_battery_probe':
drivers/power/twl4030_bci_battery.c:911: error: dereferencing pointer to incomplete type
Signed-off-by: Vikram Pandita <vikram.pandita@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>