e1000e: remove the redundant value assignment in e1000_update_nvm_checksum_spt

Both of the statements are value assignment of the variable act_offset.
The first value assignment is overwritten by the second and is useless.
Remove it.
Reported-by: Tosk Robot <tencent_os_robot@tencent.com>
Signed-off-by: Kaixu Xia <kaixuxia@tencent.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/e1000e/ich8lan.c

@@ -3886,13 +3886,6 @@ static s32 e1000_update_nvm_checksum_spt(struct e1000_hw *hw)
 	if (ret_val)
 		goto release;
 
-	/* And invalidate the previously valid segment by setting
-	 * its signature word (0x13) high_byte to 0b. This can be
-	 * done without an erase because flash erase sets all bits
-	 * to 1's. We can write 1's to 0's without an erase
-	 */
-	act_offset = (old_bank_offset + E1000_ICH_NVM_SIG_WORD) * 2 + 1;
-
 	/* offset in words but we read dword */
 	act_offset = old_bank_offset + E1000_ICH_NVM_SIG_WORD - 1;
 	ret_val = e1000_read_flash_dword_ich8lan(hw, act_offset, &dword);