lp8727_charger: Add supported i2c functionality check routine

lp8727 i2c r/w functions are based on SMBUS I2C BLOCK. So the driver needs to
check whether i2c bus supports this functionality or not.

Signed-off-by: Woogyom Kim <milo.kim@ti.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>