STM32L4:  Add IWDG peripheral.  This is the same as for STM32 except that prescale and reload can be
changed after watchdog has been started, as this seems to work on L4.

netdb: Fix time info in lib_dnscache.c

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Signed-off-by: Masayuki Ishikawa <masayuki.ishikawa@gmail.com>

Bug fix by sony

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Jira: PDFW15IS-265
Coverity-ID: 10590 10589
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

Jira: PDFW15IS-265
Coverity-ID: 10597
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

Jira: PDFW15IS-265
Coverity-ID: 10696
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>

This is based on a patch by Taras Drozdovsky.  Basically, the delay that was added during the integration of the CDC/ACM host driver was interfering with streaming audio.  That delay was put there to prevent build endpoints from hogging the system bandwidth.  So what do we do?  Do we hog the bandwidth or do we insert arbitrarity delays.  I think both ideas such.

network IOCTL commands:  The only place in net/netdev/netdev_ioctl.c where the interface state should change is for SIOCSIFFLAGS. the other ones .. SIOCSIFADDR, SIOSLIFADDR, SIODIFADDR ..  should not change the link state.