According to offical LPC4350 document, following description may be incorrect.
29 P8_3 LCDVD20, GPIO5[ 22 ]
30 P8_2 LCDVD21, GPIO5[ 12 ]
31 P8_1 LCDVD22, GPIO5[ 21 ]
32 P8_0 LCDVD23, GPIO5[ 20 ]

it confused with following description in same document.

21 P8_3 LCDVD12, GPIO4[ 3 ]
61 P8_2 MCL0, GPIO4[ 2 ]
60 P8_1 MCL1, GPIO4[ 1 ]
50 P8_0 GPIO4[ 0 ], MCI2

I guess it should be like :
29 PB_3 LCDVD20, GPIO5[ 22 ]
30 PB_2 LCDVD21, GPIO5[ 12 ]
31 PB_1 LCDVD22, GPIO5[ 21 ]
32 PB_0 LCDVD23, GPIO5[ 20 ]

is right?