twl4030: make twl4030_i2c_read_u8 prototype consistent

u-boot standard i2c read prototype is
i2c_read(addr, reg, 1, &buf, 1)

twl4030_i2c_read_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:
twl4030_i2c_read_u8(u8 addr, u8 reg, u8 *val)

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