usb: dwc3: of-simple: mark PM functions as __maybe_unused

usb: dwc3: of-simple: mark PM functions as __maybe_unused

[Anders Roxell]

The suspend/resume functions are not referenced when power messagement
is enabled:
  CC      drivers/video/fbdev/matrox/matroxfb_DAC1064.o
drivers/usb/dwc3/dwc3-of-simple.c:223:12: warning: ‘dwc3_of_simple_resume’ defined but not used [-Wunused-function]
 static int dwc3_of_simple_resume(struct device *dev)
            ^~~~~~~~~~~~~~~~~~~~~
drivers/usb/dwc3/dwc3-of-simple.c:213:12: warning: ‘dwc3_of_simple_suspend’ defined but not used [-Wunused-function]
 static int dwc3_of_simple_suspend(struct device *dev)
            ^~~~~~~~~~~~~~~~~~~~~~
This marks them as __maybe_unused to let the compiler drop the function
without complaining.

Fixes: 76251db86561 ("usb: dwc3: of-simple: reset host controller at suspend/resume")
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
---
 drivers/usb/dwc3/dwc3-of-simple.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc3/dwc3-of-simple.c b/drivers/usb/dwc3/dwc3-of-simple.c
index 40bf9e0bbc59..8f6d39463e99 100644
--- a/drivers/usb/dwc3/dwc3-of-simple.c
+++ b/drivers/usb/dwc3/dwc3-of-simple.c
@@ -210,7 +210,7 @@ static int dwc3_of_simple_runtime_resume(struct device *dev)
 	return 0;
 }
 
-static int dwc3_of_simple_suspend(struct device *dev)
+static int __maybe_unused dwc3_of_simple_suspend(struct device *dev)
 {
 	struct dwc3_of_simple *simple = dev_get_drvdata(dev);
 
@@ -220,7 +220,7 @@ static int dwc3_of_simple_suspend(struct device *dev)
 	return 0;
 }
 
-static int dwc3_of_simple_resume(struct device *dev)
+static int __maybe_unused dwc3_of_simple_resume(struct device *dev)
 {
 	struct dwc3_of_simple *simple = dev_get_drvdata(dev);