nhk8815: fix build errors

Fix:
common/libcommon.o: In function `cread_line':
/home/ag/git/u-boot/common/main.c:695: undefined reference to `get_ticks'
/home/ag/git/u-boot/common/main.c:695: undefined reference to `get_tbclk'
/home/ag/git/u-boot/common/main.c:698: undefined reference to `get_ticks'

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Cc: Alessandro Rubini <rubini@unipv.it>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Alessandro Rubini <rubini@unipv.it>

arch/arm/cpu/arm926ejs/nomadik/timer.c

@@ -75,3 +75,13 @@ void __udelay(unsigned long usec)
 	while ((signed)(end - READ_TIMER()) > 0)
 		;
 }
+
+unsigned long long get_ticks(void)
+{
+	return get_timer(0);
+}
+
+ulong get_tbclk(void)
+{
+	return CONFIG_SYS_HZ;
+}