xtensa: cleanup ccount frequency tracking

Remove unused nsec_per_ccount, and rename ccount_per_jiffy to ccount_preq.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Chris Zankel <chris@zankel.net>

arch/xtensa/kernel/platform.c

@@ -41,6 +41,6 @@ _F(void, pcibios_init, (void), { });
 _F(void, calibrate_ccount, (void),
 {
 	pr_err("ERROR: Cannot calibrate cpu frequency! Assuming 10MHz.\n");
-	ccount_per_jiffy = 10 * (1000000UL/HZ);
+	ccount_freq = 10 * 1000000UL;
 });
 #endif