screen_test: Fixed bug with SPI timing.
screen_test: Fixed bug with SPI timing.

The SPI module uses the following parameters between bytes:
  pcsToSckDelayInNanoSec
  lastSckToPcsDelayInNanoSec
  betweenTransferDelayInNanoSec

So my small value of 4nS for pcsToSckDelayInNanoSec meant that between
bytes the clock dropped and rose again immediately, causing a glitch.

Additionally if you don't use kDSPI_MasterPcsContinuous in configFlags
for the transfer, the CS de-asserts between bytes.

andrewparlane/kinetis_test_projects,andrewparlane/kinetis_test_projects