bnxt_en: Fix build error for kernesl without RTC-LIB

bnxt_hwrm_fw_set_time() now returns -EOPNOTSUPP when built for kernel
without RTC_LIB.  Setting the firmware time is not critical to the
successful completion of the firmware update process.
Signed-off-by: NRob Swindell <Rob.Swindell@broadcom.com>
Signed-off-by: NMichael Chan <michael.chan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -4323,6 +4323,7 @@ static int bnxt_hwrm_ver_get(struct bnxt *bp)
 
 int bnxt_hwrm_fw_set_time(struct bnxt *bp)
 {
+#if IS_ENABLED(CONFIG_RTC_LIB)
 	struct hwrm_fw_set_time_input req = {0};
 	struct rtc_time tm;
 	struct timeval tv;
@@ -4340,6 +4341,9 @@ int bnxt_hwrm_fw_set_time(struct bnxt *bp)
 	req.minute = tm.tm_min;
 	req.second = tm.tm_sec;
 	return hwrm_send_message(bp, &req, sizeof(req), HWRM_CMD_TIMEOUT);
+#else
+	return -EOPNOTSUPP;
+#endif
 }
 
 static int bnxt_hwrm_port_qstats(struct bnxt *bp)