According to iMX6DQRM chapter 46 (On-Chip OTP Controller), the UID field is located at offsets 0x410 and 0x420 from the base address of the OCOTP. That is: OTP Bank0 Word1 - contains the first word of the UID OTP Bank0 Word2 - contains the second word of the UID.
021bc410: d72d7372 d72d7372 d72d7372 d72d7372 rs-.rs-.rs-.rs-.
|021bc420: 906709d4 906709d4 906709d4 906709d4||..g...g...g...g.|
Comparing to the read information under Linux shell:
Serial : 906709d4d72d7372
The value is identical from uboot and linux kernel reading back.