usb/isp1760: declare schedule_ptds() and errata2_function() static

Fix two problems detected by the sparse code analyser:

|drivers/usb/host/isp1760-hcd.c:935:6: warning: symbol 'schedule_ptds' was not declared. Should it be static?
|drivers/usb/host/isp1760-hcd.c:1288:6: warning: symbol 'errata2_function' was not declared. Should it be static?

Signed-off-by: Arvid Brodin <arvid.brodin@xdin.com>
Signed-off-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>