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

fdts/stm32mp15-ddr3-1x4Gb-1066-binG.dtsi

@@ -15,7 +15,7 @@
  * Save Date: 2020.02.20, save Time: 18:45:20
  */
 
-#define DDR_MEM_NAME	"DDR3-DDR3L 16bits 533000Khz"
+#define DDR_MEM_NAME	"DDR3-DDR3L 16bits 533000kHz"
 #define DDR_MEM_SPEED	533000
 #define DDR_MEM_SIZE	0x20000000
 

fdts/stm32mp15-ddr3-2x4Gb-1066-binG.dtsi

@@ -15,7 +15,7 @@
  * Save Date: 2020.02.20, save Time: 18:49:33
  */
 
-#define DDR_MEM_NAME	"DDR3-DDR3L 32bits 533000Khz"
+#define DDR_MEM_NAME	"DDR3-DDR3L 32bits 533000kHz"
 #define DDR_MEM_SPEED	533000
 #define DDR_MEM_SIZE	0x40000000