refactor(nan): use shared nan_key_type_t from esp_wifi_driver.h

The NAN key-type selectors are defined by the blob in esp_wifi_driver.h
(nan_key_type_t), which nan_i.h already includes. Add the group-integrity
key types NAN_KEY_ND_IGTK (3) and NAN_KEY_ND_BIGTK (4) there to match the
blob, and drop the duplicate host definitions from nan_i.h so a single
shared enum is used. Resolves the review request to declare these in
nan_key_type_t and avoids redefining the typedef.

components/wpa_supplicant/esp_supplicant/src/esp_wifi_driver.h

@@ -238,6 +238,8 @@ typedef enum {
     NAN_KEY_ND_TK = 0,
     NAN_KEY_ND_GTK,
     NAN_KEY_NM_TK,
+    NAN_KEY_ND_IGTK,        /* 3 - NAN Integrity Group Temporal Key (BIP-CMAC-128) */
+    NAN_KEY_ND_BIGTK,       /* 4 - NAN Beacon Integrity Group Temporal Key (BIP-CMAC-128) */
 } nan_key_type_t;
 
 typedef struct {