xo1.75 can't read/write registers correctly in debugfs

[Chia-Hsiu Chang]

Hello Libertas developers,
   Did anyone have xo1.75? I found debugfs not work correctly with
Marvell sd8686.
   It always shows zero when cat /lbs_wireless/waln0/registers/rdmac .
   I can echo a number to wrmac in xo1.5 and read from rdmac with no
problem but xo1.75 can't.
   Is there has any issues in arm platform, or just forget to enable
some debug configurations?
   I am eager for any answers, and appreciate for any help, thanks!
Thanks
Color