You must report this contribution. It is required to be present on Form 8889 included with your 2021 tax return.
To report this contribution without entering the W-2, in the HSA section tell TurboTax that your employer told you about other contributions, then enter the code-W amount in the box for employer and payroll contributions for 2021 not reported in box 12 of your W-2. This will cause the amount to appear as required on Form 8889 line 9 that same as it would had you entered the W-2. Do not enter this as a personal contribution.
