ice: report timeout length for erasing during devlink flash

When erasing, notify userspace of how long we will potentially take to
erase a module. Doing so allows userspace to report the timeout, giving
a clear indication of the upper time bound of the operation.

Since we're re-using the erase timeout value, make it a macro rather
than a magic number.

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Shannon Nelson <snelson@pensando.io>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>