iwlwifi: explicitly track whether INIT uCode was run

Remove IWL_UCODE_NONE from enum iwl_ucode_type which,
by being the default value in 0-initialized memory,
implicitly allowed us to track whether any uCode had
ever been loaded successfully (which would have been
the INIT uCode) and instead explicitly track whether
or not INIT uCode has been run.

Signed-off-by: David Spinadel <david.spinadel@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>