iwlwifi: runtime: sync FW and host clocks for logs

For sync we send a marker cmd every <defined throughout debugfs> seconds.
The trigger for getting gp2 clock values from the FW is set by
writing to debugfs a periodic time in seconds,
if value zero is written, only one request would be sent
and the timer would be canceled.

Also added a small infrastructure for debugfs runtime code.

Signed-off-by: Mordechay Goodstein <mordechay.goodstein@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>