How can we use SDA and SCL pins as RX and TX pins of UART in MCF5206E
This is a 22 year old design. All the pin functions are fixed. Being able to reassign pins to different function modules (and use them as GPIOs) was only added in later ColdFire models.
You could always use an external chip which provides a UART function and has an I2C (aka M-BUS) interface.. Which is just about any modern single-chip microprocessor programmed to do that.
Or, already set up to do exactly this (thank you Google), the NXP SC16IS740:
Yes, as Tom metioned, MCF5206 is quite old and all pins do not have the multi-fucntion as the later ColdFire parts are. So you can not use the SDA/SCL as UART RX & TX.
Retrieving data ...