Kirkwood: allow to override CONFIG_SYS_TCLK

This patch allow to override CONFIG_SYS_TCLK from board configuration
files. This is needed for the Network Space v2 which use a non standard
core clock frequency (166MHz instead of 200MHz for a 6281 SoC).

As a possible enhancement for 6281 and 6282 devices, TCLK could be
dynamically detected by checking the Sample at Reset register bit 21.

Additionally this patch fix a typo.

Signed-off-by: Simon Guinot <sguinot@lacie.com>
Acked-by: Prafulla Wadaskar <Prafulla@marvell.com>

arch/arm/include/asm/arch-kirkwood/kw88f6281.h

@@ -27,11 +27,13 @@
 #ifndef _ASM_ARCH_KW88F6281_H
 #define _ASM_ARCH_KW88F6281_H
 
-/* SOC specific definations */
+/* SOC specific definitions */
 #define KW88F6281_REGS_PHYS_BASE	0xf1000000
 #define KW_REGS_PHY_BASE		KW88F6281_REGS_PHYS_BASE
 
-/* TCLK Core Clock defination*/
-#define CONFIG_SYS_TCLK	  200000000 /* 200MHz */
+/* TCLK Core Clock definition */
+#ifndef CONFIG_SYS_TCLK
+#define CONFIG_SYS_TCLK	200000000 /* 200MHz */
+#endif
 
 #endif /* _ASM_ARCH_KW88F6281_H */