When the switch is set to operate in the Multi Chip Addressing Mode we
cannot access the GLOBAL2 register directly.

Despite the comment in code (which was misleading), the indirect access is
only used to read the switch CONFIG data from the scrap register and not
for the GLOBAL2 access.

Use the dsa data to define when the switch is in the Multi Chip Addressing
Mode (a even address different than zero).

While here fix a typo.

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