ipq40xx: fix high resolution timer

ipq40xx: fix high resolution timer

Cherry-picked from CAF QSDK repo.
see 090-ipq40xx-fix-high-resolution-timer.patch

Original commit message:
The kernel is failing in switching the timer for high resolution
mode and clock source operates in 10ms resolution. The always-on
property needs to be given for timer device tree node to make
clock source working in 1ns resolution.

Signed-off-by: Pavel Kubelun <be.dissent@gmail.com>
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
[changed authorship of main patch to pavel and cherry-picked
patch to Abhishek Sahu]