iwlwifi: mvm: fix harmless smatch / coccinelle warnings

Don't check if mvm->fw->cs is NULL since it can't be.
cs is an array member of iwl_fw, it can't be NULL.

Use memset(ptr, 0, sizeof(*ptr)); instead of
memset(ptr, 0, sizeof(struct ptr_type));

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/mvm/mac80211.c b/drivers/net/wireless/iwlwifi/mvm/mac80211.c
index b61d5a2..e9eff30 100644
--- a/drivers/net/wireless/iwlwifi/mvm/mac80211.c
+++ b/drivers/net/wireless/iwlwifi/mvm/mac80211.c
@@ -262,7 +262,7 @@
 	mvm->rts_threshold = IEEE80211_MAX_RTS_THRESHOLD;
 
 	/* currently FW API supports only one optional cipher scheme */
-	if (mvm->fw->cs && mvm->fw->cs->cipher) {
+	if (mvm->fw->cs->cipher) {
 		mvm->hw->n_cipher_schemes = 1;
 		mvm->hw->cipher_schemes = mvm->fw->cs;
 	}