spi: ti_qspi: fix unit address

Fix unit address to match the first address specified in the reg
property of the node in example.

Signed-off-by: Kangmin Park <l4stpr0gr4m@gmail.com>
Link: https://lore.kernel.org/r/1589873541-5587-1-git-send-email-l4stpr0gr4m@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>