usb: host: xhci-plat: release mem region while removing module

commit 5388a3a5faba8dfa69e5f06c3a415d373c1a4316 upstream.

Do a release_mem_region of the hcd resource. Without this the
subsequent insertion of module fails in request_mem_region.

Signed-off-by: George Cherian <george.cherian@ti.com>
Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>