fix(fdts stm32mp1): use 'kHz' as kilohertz abbreviation

The kilohertz unit abbreviation should read 'kHz' in DDR
settings files of stm32mp15.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Change-Id: Ifa363094f58dd943ef78c653c3e470a216739b41
2 files changed