M451 series can classify by M45xD/M45xC and M45xG/M45xE. To support this
classification:
1.  Create TARGET_M45xD_M45xC and TARGET_M45xG_M45xE targets.
2.  Mark NUMAKER_PFM_M453 belongs to TARGET_M45xG_M45xE by 'extra_labels_add'
    in targets.json.
3.  Fix pin name table according to the classification.
4.  Fix pinmap table according to the classification.