twl6030: twl6030_i2c_[read|write]_u8 prototype consistent

u-boot standard i2c register access prototype is
i2c_read(addr, reg, 1, &buf, 1)
i2c_reg_write(u8 addr, u8 reg, u8 val)

twl6030_i2c_read_u8(u8 addr, u8 *val, u8 reg)
twl6030_i2c_write_u8(u8 addr, u8 val, u8 reg)
does not provide consistency, so switch the prototype to be
consistent with rest of u-boot i2c operations:
twl6030_i2c_read_u8(u8 addr, u8 reg, u8 *val)
twl6030_i2c_write_u8(u8 addr, u8 reg, u8 val)

Signed-off-by: Nishanth Menon <nm@ti.com>