ehci: fix EHCI host controller initialization sequence

ehci: fix EHCI host controller initialization sequence

According to EHCI spec, EHCI HC clears USBSTS.HCHalted whenever
USBCMD.RS=1.

However, it is a good practice to wait some time after setting USBCMD.RS
(approximately 100ms) until USBSTS.HCHalted become zero.

Without this waiting, VirtualBox's EHCI virtual HC accidentally hangs
(see BugLink).

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=211095
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Eugene Korenevsky <ekorenevsky@astralinux.ru>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20210110173609.GA17313@himera.home
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>