usb: host: tegra: defer ehci cpu freq. boost work

usb: host: tegra: defer ehci cpu freq. boost work

Delayed work is getting executed even before DVFS initialization
(which happens in late_initcall after all devices initialization
has completed). So device fails in changing the CPU rate, as
regulator is still not present, with following warning -

"Increasing CPU rate while regulator is not ready is not allowed"

Currently DVFS initialization, initializes both CPU and Core, and
only Core is dependent on completion of device initialization.
So ideally CPU init. can be done much earlier which will resolve
this issue. This is still under discussion.

This patch defers the cpu rate change by ehci even further so that
DVFS initialization gets completed before pm_qos_update_request.

Bug 1352877

Change-Id: Ia21af01c4bc915e1120fc72917428d9fdc26b38d
Signed-off-by: Shreshtha Sahu <ssahu@nvidia.com>
Reviewed-on: http://git-master/r/304198
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Rakesh Babu Bodla <rbodla@nvidia.com>
Reviewed-by: Venkat Moganty <vmoganty@nvidia.com>