MemoryViewWidget: Remove unnecessary column

[Pokechu22]

This column would end up containing junk data after changing the data type, specifically whatever data was already in that column in the previous datatype.

Column 0 is used for a breakpoint indicator (if the entire row has breakpoints). Column 1 is the address. Columns 2 through 2+n, exclusive, are used for the data for the row, where n varies by data type (for U8 it's 16, but for float and U32 it's 4); for example, with float, columns 2, 3, 4, and 5 are in use. Thus, there are 6 columns (0 through 5), which is 2+4, not 3+4.

Before: First set to U8, then change to float
After: First set to U8, then change to float

[dolphin-emu-bot]

FifoCI detected that this change impacts graphical rendering. Here are the behavior differences detected by the system:

• jj-awae-mirrored on uberogl-lin-radeon: diff

_{^{automated-fifoci-reporter}}