e1000e: Delete redundant variable definitions

The local variable is not used elsewhere in the function

The clang_analyzer complains as follows:

drivers/net/ethernet/intel/e1000e/ptp.c:241:19 warning

Value stored to 'hw' during its initialization is never read

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: luo penghao <luo.penghao@zte.com.cn>

drivers/net/ethernet/intel/e1000e/ptp.c

@@ -238,7 +238,6 @@ static void e1000e_systim_overflow_work(struct work_struct *work)
 {
 	struct e1000_adapter *adapter = container_of(work, struct e1000_adapter,
 						     systim_overflow_work.work);
-	struct e1000_hw *hw = &adapter->hw;
 	struct timespec64 ts;
 	u64 ns;