sh: sh2: Change CONFIG_SYS_HZ to CONFIG_SH_CMT_CLK_FREQ

CONFIG_SYS_HZ of SH2 is not used as frequency of base timer. This is the
correct clock of CMT.
This changes from CONFIG_SYS_HZ to CONFIG_SH_CMT_CLK_FREQ, in order to use
CONFIG_SYS_HZ as clock of CMT.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
diff --git a/arch/sh/lib/time_sh2.c b/arch/sh/lib/time_sh2.c
index be3896c..4b1f47b 100644
--- a/arch/sh/lib/time_sh2.c
+++ b/arch/sh/lib/time_sh2.c
@@ -84,5 +84,5 @@
 
 unsigned long get_tbclk(void)
 {
-	return CONFIG_SYS_HZ;
+	return CONFIG_SH_CMT_CLK_FREQ;
 }