usb: storage: fix build warnings !CONFIG_PM

Functions fw5895_init() and config_autodelink_before_power_down() are used
only when CONFIG_PM is defined.

drivers/usb/storage/realtek_cr.c:699:13: warning: 'fw5895_init' defined but not used [-Wunused-function]
drivers/usb/storage/realtek_cr.c:629:12: warning: 'config_autodelink_before_power_down' defined but not used [-Wunused-function]

Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>