ice: devlink: add shadow-ram region to snapshot Shadow RAM

We have a region for reading the contents of the NVM flash as
a snapshot. This region does not allow reading the Shadow RAM, as it
always passes the FLASH_ONLY bit to the low level firmware interface.

Add a separate shadow-ram region which will allow snapshot of the
current contents of the Shadow RAM. This data is built from the NVM
contents but is distinct as the device builds up the Shadow RAM during
initialization, so being able to snapshot its contents can be useful
when attempting to debug flash related issues.

Fix the comment description of the nvm-flash region which incorrectly
stated that it filled the shadow-ram region, and add a comment
explaining that the nvm-flash region does not actually read the Shadow
RAM.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>