Revert "xhci: Add grace period after xHC start to prevent premature runtime suspend."

This reverts commit c2f4a72d which is
commit 33e321586e37b642ad10594b9ef25a613555cd08 upstream.

It breaks the Android kernel ABI and shouldn't be needed for any normal
Android devices.  If this is needed in the future, it can be brought
back in an ABI-stable manner.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I6654f57f1f234421ec8573dc741e3e8bdb7e287b