[Enhancement] Better configuration for partitioning multiple emummc

[Sayora77]

It would be very helpful to allow set different emummc sizes (for example: a full one for online use as nintendo collects nand size, and a small one to save space) Currently they both have to be the same size and attempting to manipulate the partitions on a computer seems to break android and linux. Perhaps it could work well with 2/3 adjacent sliders to set them individually, and one set to zero if only one is desired.