USB: cypress_m8: fix potential scheduling while atomic

Remove erroneous call to usb_clear_halt which is blocking and cannot be
used in interrupt context.

This code has possibly never been executed as it would cause an oops if
it was. Simply treat a stalled-endpoint error as any other error
condition.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>