usb: Remove 200 ms delay in usb_hub_port_connect_change()

This patch removes 2 mdelay(200) calls from usb_hub_port_connect_change().
These delays don't seem to be necessary. At least not in my tests. Here
the number for a custom x86 Bay Trail board (not in mainline yet) with
a quite large and complex USB hub infrastructure.

Without this patch:
starting USB...
USB0:   USB EHCI 1.00
scanning bus 0 for devices... 9 USB Device(s) found

time: 28.415 seconds

With this patch:
starting USB...
USB0:   USB EHCI 1.00
scanning bus 0 for devices... 9 USB Device(s) found

time: 24.003 seconds

So ~4.5 seconds of USB scanning time reduction.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Simon Glass <sjg@chromium.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
Cc: Marek Vasut <marex@denx.de>