I have changed clock to 24MHz, and trying to enable uart_pal. LINFlexD_2 is used in the given example uart_pal_mpc5748g, Where I have configured with LINFlexD_7 instead of LINFlexD_2.
I don't have a board with 24MHz crystal, so I can't test your project directly without changes. What is not working exactly? If you use an oscilloscope, is anything send out? When you debug the code, what can you see?