ehci-hcd: Disable memory-write-invalidate when the driver is removed

ehci-hcd: Disable memory-write-invalidate when the driver is removed

The driver calls pci_set_mwi to enable memory-write-invalidate when it
is initialized, but does not call pci_clear_mwi when it is removed. Many
other drivers calls pci_clear_mwi when pci_set_mwi is called, such as
r8169, 8139cp and e1000.

This patch adds a function "ehci_pci_remove" to remove the pci driver.
This function calls pci_clear_mwi and usb_hcd_pci_remove, which can
fix the problem.

Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>