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

This reverts commit 5a603f4c which is
commit 33e32158 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