USB: fix build error when CONFIG_PM_SLEEP isn't enabled

USB: fix build error when CONFIG_PM_SLEEP isn't enabled

This patch fixes a build error that occurs when CONFIG_PM is enabled
and CONFIG_PM_SLEEP isn't:

>> drivers/usb/host/ohci-pci.c:294:10: error: 'usb_hcd_pci_pm_ops' undeclared here (not in a function)
      .pm = &usb_hcd_pci_pm_ops

Since the usb_hcd_pci_pm_ops structure is defined and used when
CONFIG_PM is enabled, its declaration should not be protected by
CONFIG_PM_SLEEP.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-by: kbuild test robot <fengguang.wu@intel.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>