mwifiex: fix static checker warnings

"oui_type" in structure "ieee_types_vendor_header" is not used separately,
so include it in "oui" array. Now complete oui will be compared fixing
following warnings.

drivers/net/wireless/mwifiex/sta_ioctl.c:1410 mwifiex_set_gen_ie_helper()
        error: memcmp() 'pvendor_ie->oui' too small (3 vs 4)
drivers/net/wireless/mwifiex/sta_ioctl.c:1435 mwifiex_set_gen_ie_helper()
        error: memcmp() 'pvendor_ie->oui' too small (3 vs 4)
drivers/net/wireless/mwifiex/scan.c:1177 mwifiex_update_bss_desc_with_ie()
        error: memcmp() 'vendor_ie->vend_hdr.oui' too small (3 vs 4)
drivers/net/wireless/mwifiex/scan.c:1185 mwifiex_update_bss_desc_with_ie()
        error: memcmp() 'vendor_ie->vend_hdr.oui' too small (3 vs 4)

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Avinash Patil <patila@marvell.com>
Signed-off-by: Kiran Divekar <dkiran@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/fw.h

@@ -993,8 +993,7 @@ struct mwifiex_ie_types_wmm_queue_status {
 struct ieee_types_vendor_header {
 	u8 element_id;
 	u8 len;
-	u8 oui[3];
-	u8 oui_type;
+	u8 oui[4];	/* 0~2: oui, 3: oui_type */
 	u8 oui_subtype;
 	u8 version;
 } __packed;