hwrng: omap3-rom - Fix unused function warnings

When runtime-pm is disabled, we get a few harmless warnings:

drivers/char/hw_random/omap3-rom-rng.c:65:12: error: unused function 'omap_rom_rng_runtime_suspend' [-Werror,-Wunused-function]
drivers/char/hw_random/omap3-rom-rng.c:81:12: error: unused function 'omap_rom_rng_runtime_resume' [-Werror,-Wunused-function]

Mark these functions as __maybe_unused so gcc can drop them
silently.

Fixes: 8d9d4bdc ("hwrng: omap3-rom - Use runtime PM instead of custom functions")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/char/hw_random/omap3-rom-rng.c

@@ -62,7 +62,7 @@ static int omap3_rom_rng_read(struct hwrng *rng, void *data, size_t max, bool w)
 	return r;
 }
 
-static int omap_rom_rng_runtime_suspend(struct device *dev)
+static int __maybe_unused omap_rom_rng_runtime_suspend(struct device *dev)
 {
 	struct omap_rom_rng *ddata;
 	int r;
@@ -78,7 +78,7 @@ static int omap_rom_rng_runtime_suspend(struct device *dev)
 	return 0;
 }
 
-static int omap_rom_rng_runtime_resume(struct device *dev)
+static int __maybe_unused omap_rom_rng_runtime_resume(struct device *dev)
 {
 	struct omap_rom_rng *ddata;
 	int r;