iwlwifi: correct Kconfig to prevent following entries from not indenting

    defining configurations that are not visible caused the following
    entries to not be indented. changing the tree structure to name the
    top level selection and have all others reference IWLWIFI directly
    corrects this issue.

Signed-off-by: Jay Sternberg <jay.e.sternberg@linux.intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>