MAX7219 Update Code sends frame buffer 8 times

[mringwal]

multibus/example/python/multibus_spi_master_max7219_test.py

Line 230 in febf778

spi.write(1, data)

The code constructs the SPI commands row by row, so there should be 8 SPI messages of 8 bytes each.
However, The code sends each line four times though (totaling 32 messages). To fix: unindent the call to SPI write / only send once per row.