usb: core: Drive resume for 20ms for devices behind external hub

skip_extended_resume_delay module parameter is completely skipping
delay required to drive bus resume for devices behind the external
hub(s). This is causing resume failure for the device. Fix the
issue by driving resume for 20ms.

Change-Id: I13ba8094c7eab119f1d41ebc9e15c9aa91096201
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>