xtensa: use HZ_PER_MHZ in platform_calibrate_ccount

Replace the hardcoded 1000000UL with the HZ_PER_MHZ unit macro, and add
a space in "10 MHz" to improve the readability of the error message.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Message-Id: <20250915120540.2150841-3-thorsten.blum@linux.dev>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

Author: toblux

arch/xtensa/kernel/platform.c

@@ -14,6 +14,7 @@
 
 #include <linux/printk.h>
 #include <linux/types.h>
+#include <linux/units.h>
 #include <asm/platform.h>
 #include <asm/timex.h>
 
@@ -38,7 +39,7 @@ void __weak platform_idle(void)
 #ifdef CONFIG_XTENSA_CALIBRATE_CCOUNT
 void __weak platform_calibrate_ccount(void)
 {
-	pr_err("ERROR: Cannot calibrate cpu frequency! Assuming 10MHz.\n");
-	ccount_freq = 10 * 1000000UL;
+	pr_err("ERROR: Cannot calibrate cpu frequency! Assuming 10 MHz.\n");
+	ccount_freq = 10 * HZ_PER_MHZ;
 }
 #endif