ARM: dts: stm32: Fix cosmetic typo: use 'kHz' as kilohertz abbreviation

The kilohertz unit abbreviation should read 'kHz'.
Note to STM32 team: modified files were generated, it may be worth
to fix STM32CubeMX tool.

Signed-off-by: Fabrice GIRARDOT <fabrice.girardot@flowbird.group>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
2 files changed