igb: zero hwtstamp by default

Clang static analysis reports this representative issue
igb_ptp.c:997:3: warning: The left operand of '+' is a
  garbage value
  ktime_add_ns(shhwtstamps.hwtstamp, adjust);
  ^            ~~~~~~~~~~~~~~~~~~~~

shhwtstamps.hwtstamp is set by a call to
igb_ptp_systim_to_hwtstamp().  In the switch-statement
for the hw type, the hwtstamp is zeroed for matches
but not the default case.  Move the memset out of
switch-statement.  This degarbages the default case
and reduces the size.

Some whitespace cleanup of empty lines

Signed-off-by: Tom Rix <trix@redhat.com>
Tested-by: Gurucharan G <gurucharanx.g@intel.com> (A Contingent worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igb/igb_ptp.c

@@ -165,23 +165,21 @@ static void igb_ptp_systim_to_hwtstamp(struct igb_adapter *adapter,
 	unsigned long flags;
 	u64 ns;
 
+	memset(hwtstamps, 0, sizeof(*hwtstamps));
+
 	switch (adapter->hw.mac.type) {
 	case e1000_82576:
 	case e1000_82580:
 	case e1000_i354:
 	case e1000_i350:
 		spin_lock_irqsave(&adapter->tmreg_lock, flags);
-
 		ns = timecounter_cyc2time(&adapter->tc, systim);
-
 		spin_unlock_irqrestore(&adapter->tmreg_lock, flags);
 
-		memset(hwtstamps, 0, sizeof(*hwtstamps));
 		hwtstamps->hwtstamp = ns_to_ktime(ns);
 		break;
 	case e1000_i210:
 	case e1000_i211:
-		memset(hwtstamps, 0, sizeof(*hwtstamps));
 		/* Upper 32 bits contain s, lower 32 bits contain ns. */
 		hwtstamps->hwtstamp = ktime_set(systim >> 32,
 						systim & 0xFFFFFFFF);