[posix] rename and move the configuration of host-rcp time sync interval (#8630)

This commit renames the configuration `RCP_TIME_OFFSET_CHECK_INTERVAL`
to `OPENTHREAD_POSIX_CONFIG_RCP_TIME_SYNC_INTERVAL` and moves it to
posix configuration file because this configuration may need to be
configured on different platforms.

src/lib/spinel/radio_spinel_impl.hpp

@@ -64,18 +64,11 @@
 #ifndef US_PER_S
 #define US_PER_S (MS_PER_S * US_PER_MS)
 #endif
-#ifndef NS_PER_US
-#define NS_PER_US 1000
-#endif
 
 #ifndef TX_WAIT_US
 #define TX_WAIT_US (5 * US_PER_S)
 #endif
 
-#ifndef RCP_TIME_OFFSET_CHECK_INTERVAL
-#define RCP_TIME_OFFSET_CHECK_INTERVAL (60 * US_PER_S)
-#endif
-
 using ot::Spinel::Decoder;
 
 namespace ot {
@@ -2234,7 +2227,7 @@ void RadioSpinel<InterfaceType, ProcessContextType>::CalcRcpTimeOffset(void)
 
     mRadioTimeOffset      = (remoteTimestamp - ((localRxTimestamp / 2) + (localTxTimestamp / 2)));
     mIsTimeSynced         = true;
-    mRadioTimeRecalcStart = localRxTimestamp + RCP_TIME_OFFSET_CHECK_INTERVAL;
+    mRadioTimeRecalcStart = localRxTimestamp + OPENTHREAD_POSIX_CONFIG_RCP_TIME_SYNC_INTERVAL;
 
 exit:
     LogIfFail("Error calculating RCP time offset: %s", error);

src/posix/platform/openthread-posix-config.h

@@ -362,4 +362,15 @@
 #define OPENTHREAD_POSIX_CONFIG_PRODUCT_CONFIG_FILE "src/posix/platform/openthread.conf.example"
 #endif
 
+/**
+ * @def OPENTHREAD_POSIX_CONFIG_RCP_TIME_SYNC_INTERVAL
+ *
+ * This setting configures the interval (in units of microseconds) for host-rcp
+ * time sync. The host will recalculate the time offset between host and RCP
+ * every interval.
+ *
+ */
+#ifndef OPENTHREAD_POSIX_CONFIG_RCP_TIME_SYNC_INTERVAL
+#define OPENTHREAD_POSIX_CONFIG_RCP_TIME_SYNC_INTERVAL (60 * 1000 * 1000)
+#endif
 #endif // OPENTHREAD_PLATFORM_CONFIG_H_