[MIPS] Cleanup remaining references to mips_counter_frequency.

Noticed by Samium Gromoff but his patch got stale in flight ...

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/mips-boards/generic/time.c b/arch/mips/mips-boards/generic/time.c
index 6f8a9fe..c079e2a 100644
--- a/arch/mips/mips-boards/generic/time.c
+++ b/arch/mips/mips-boards/generic/time.c
@@ -187,7 +187,7 @@
 }
 
 /*
- * Estimate CPU frequency.  Sets mips_counter_frequency as a side-effect
+ * Estimate CPU frequency.  Sets mips_hpt_frequency as a side-effect
  */
 static unsigned int __init estimate_cpu_frequency(void)
 {