iwlwifi: remove support for fw older than -17 and -22

FW versions older than -17 for 3160 and 7260 and older than -22 for
newer NICs are not supported anymore.  Don't load these versions
and remove code that handles them.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-7000.c b/drivers/net/wireless/intel/iwlwifi/iwl-7000.c
index aa575fb..d4b73de 100644
--- a/drivers/net/wireless/intel/iwlwifi/iwl-7000.c
+++ b/drivers/net/wireless/intel/iwlwifi/iwl-7000.c
@@ -77,9 +77,9 @@
 #define IWL3168_UCODE_API_MAX	26
 
 /* Lowest firmware API version supported */
-#define IWL7260_UCODE_API_MIN	16
-#define IWL7265_UCODE_API_MIN	16
-#define IWL7265D_UCODE_API_MIN	16
+#define IWL7260_UCODE_API_MIN	17
+#define IWL7265_UCODE_API_MIN	17
+#define IWL7265D_UCODE_API_MIN	17
 #define IWL3168_UCODE_API_MIN	20
 
 /* NVM versions */