fm10k: IS_ENABLED() is not appropriate for boolean kconfig option

Tri-states need 'if IS_ENABLED()', booleans should use 'ifdef'.

Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>