mmc, kernel 4.0.5, SDIO power management error message

On suspend, SDIO (MMC) power management fails and removes a card ("mmc2: card 0001 removed") if any of the card's functions don't support power management. Then nothing ever resumes it, so the card is lost forever. With this patch, it will also provide a useful error message ("btsdio mmc2:0001:3: pre_suspend failed (driver has no PM)"). This will save hours of diagnostic effort for anyone whose SDIO cards disappear on suspend.

@@ -918,6 +918,8 @@
 			const struct dev_pm_ops *pmops = func->dev.driver->pm;
 			if (!pmops || !pmops->suspend || !pmops->resume) {
 				/* force removal of entire card in that case */
+				dev_err(&func->dev, "pre_suspend failed "
+					"(driver has no PM)\n");
 				err = -ENOSYS;
 				break;
 			}