mediatek: mt7988: fix peripheral SPI busses

mediatek: mt7988: fix peripheral SPI busses

The clocks for SPI busses were named wrongly which resulted in the
spi-mt65xx driver not requesting them. This has apparently been
worked around by marking the clocks required for SPI0 which is used
for SPI-NOR and SPI-NAND flash chips as critical.
Fix the device tree for all 3 generic SPI host controllers and no
longer mark clocks as critical.

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
(cherry picked from commit 2b173ab730897f53539cab39e87e2b4638cb482a)