Revert "tests: kernel: update test case with sys_clock_hw_cycles_per_sec"

This reverts commit fd8ca83.

#69705
Introduced a regression in main in which
tests/subsys/logging/log_timestamp
started failing. (See
#72344
for more info).
Let's revert the PR. It can be submitted after with the issue
fixed.

Signed-off-by: Alberto Escolar Piedras <[email protected]>

Author: aescolar

tests/kernel/common/src/boot_delay.c

@@ -18,7 +18,7 @@
  */
 ZTEST(boot_delay, test_bootdelay)
 {
-	if (sys_clock_hw_cycles_per_sec() > 1000000000) {
+	if (CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC > 1000000000) {
 		/* Systems with very fast counters (like the x86 TSC)
 		 * and long firmware startup (often 10+ seconds on a
 		 * EFI PC!)  can easily roll this over during startup,

tests/kernel/threads/no-multithreading/src/main.c

@@ -11,7 +11,7 @@
 ZTEST(no_multithreading, test_k_busy_wait)
 {
 	int64_t now = k_uptime_get();
-	uint32_t watchdog = sys_clock_hw_cycles_per_sec();
+	uint32_t watchdog = CONFIG_SYS_CLOCK_HW_CYCLES_PER_SEC;
 
 	while (k_uptime_get() != now) {
 		/* Wait until uptime progresses */