kmp204x: update the CONFIG_PRAM and CONFIG_KM_RESERVED_PRAM defines

This prevents u-boot from accessing into the reserved memory areas that
we have for /var and the logbooks.
Signed-off-by: NValentin Longchamp <valentin.longchamp@keymile.com>

include/configs/km/kmp204x-common.h

@@ -139,10 +139,12 @@ unsigned long get_board_sys_clk(unsigned long dummy);
 #define CONFIG_KM_PNVRAM	0x80000
 /* physical RAM MTD size [hex] */
 #define CONFIG_KM_PHRAM		0x100000
-/* resereved pram area at the end of memroy [hex] */
-#define CONFIG_KM_RESERVED_PRAM	0x0
-/* enable protected RAM */
-#define CONFIG_PRAM		0
+/* reserved pram area at the end of memory [hex]
+ * u-boot reserves some memory for the MP boot page */
+#define CONFIG_KM_RESERVED_PRAM	0x1000
+/* set the default PRAM value to at least PNVRAM + PHRAM when pram env variable
+ * is not valid yet, which is the case for when u-boot copies itself to RAM */
+#define CONFIG_PRAM		((CONFIG_KM_PNVRAM + CONFIG_KM_PHRAM)>>10)
 
 #define CONFIG_KM_CRAMFS_ADDR	0x2000000
 #define CONFIG_KM_KERNEL_ADDR	0x1000000	/* max kernel size 15.5Mbytes */