ice: add ability to read and configure FW log data

Once logging is enabled the user should read the data from the 'data'
file. The data is in the form of a binary blob that can be sent to Intel
for decoding. To read the data use a command like:

  # cat /sys/kernel/debug/ice/0000\:18\:00.0/fwlog/data > log_data.bin

If the user wants to clear the FW log data that has been stored in the
driver then they can write any value to the 'data' file and that will clear
the data. An example is:

  # echo 34 > /sys/kernel/debug/ice/0000\:18\:00.0/fwlog/data

In addition to being able to read the data the user can configure how
much memory is used to store FW log data. This allows the user to
increase/decrease the amount of memory based on the users situation.
The data is stored such that if the memory fills up then the oldest data
will get overwritten in a circular manner. To change the amount of
memory the user can write to the 'log_size' file like this:

  # echo <value> > /sys/kernel/debug/ice/0000\:18\:00.0/fwlog/log_size

Where <value> is one of 128K, 256K, 512K, 1M, and 2M. The default value
is 1M.

The user can see the current value of 'log_size' by reading the file:

  # cat /sys/kernel/debug/ice/0000\:18\:00.0/fwlog/log_size

Signed-off-by: Paul M Stillwell Jr <paul.m.stillwell.jr@intel.com>
Tested-by: Pucha Himasekhar Reddy <himasekharx.reddy.pucha@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>