Unknown symbol __udelay (err 0) since 4.7.x

[CaptainBloodz]

Hi, using WIFI only, everything went almost smooth until 4.6.7 included.
Any later 4.7.x or 4.8.x kernel generates error as reported in dmesg:

[78584.596449] mt7630e: loading out-of-tree module taints kernel.
[78584.596544] mt7630e: Unknown symbol __udelay (err 0)

NB 2.0.8 & linux-headers-4.7 in all cases.

Any idea?.
.
Thks 4 the tremendous work done though.

Edit: CONFIG_TRIM_UNUSED_KSYMS was the culprit. smooth as silk once removed.

Plz close.

Thks again.