[electrum] Fix Trezor 1 unlocking

Summary:
2 bugs have been introduced recently that prevent the use of a Trezor 1:

• D17547 caused the pin window to close the passphrase request prematurely due to some missed legacy code
• D17555 was checking the device model using an integer instead of a string, preventing the seed entry method to be selected. As a consequence it was impossible to recover a Trezor 1.

Test Plan: Unlock a Trezor 1, wipe it, then recover it from the previous seed.

Reviewers: #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D17563