wifi: iwlwifi: mvm: move listen interval to constants

This can be moved to constants, while at it also rename
it to have a better name with MVM_ prefix.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230913145231.59823deebfda.Ied68b11ca40771d1cfc8c82ee8f9f2b9ea27da65@changeid


Signed-off-by: Johannes Berg <johannes.berg@intel.com>