mlxsw: i2c: Extend input parameters list of command API

Extend input parameters list of command API in mlxsw_i2c_cmd() in order
to support initialization commands. Up until now, only access commands
were supported by I2C driver.

Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>