USB: hub.c: Add initial_descriptor_timeout module parameter for usbcore

This patch adds initial_descriptor_timeout module parameter for usbcore.ko
to allow modify initial 64-byte USB_REQ_GET_DESCRIPTOR timeout for
non-standard devices.

For example, the SATA8000 device from DATAST0R Technology Corp
requires about 10 seconds to send reply (probably it waits until
inserted disk is ready for operation).

Also, this patch adds missing usbcore parameters to
Documentation/kernel-parameters.txt.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>