Just a heads up - if you proceed to encrypted boot, there's a typo in mx8m_encrypted_boot.txt:
Line 454: MAC offset = csf_fit_enc.bin size - Nonce/MAC size
Line 455: = 4020 - 36 = 3984 Byte
The file referenced, should be 'csf_fit_sign_enc.txt', not 'csf_fit_enc.bin'. The size in line 455: 4020 bytes are however correct.