You did not connect the 8255 as memory mapped I/O. Therefore you can't use MOVX instruction.

Rather you have to simulate all the signals as you did in the beginnig of your program.

Prior to accessing any port in 8255, you must program it with a control word.

You can find more details in the datasheet of 8255.

BTW: Why are you connecting 8255 to 8051 which already has 4 ports. 8255 was intended with microprocessors like Z80, 8085, 8086 which didn't have any port.