mmc: Standardize header file inclusion checks.

Standardize the checks for multiple MMC header file inclusion,
including adding comments to terminating #endif's, and fixing
one incorrect comment.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 1ee4424..fc24b38 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -373,5 +373,4 @@
 {
 	return host->caps & MMC_CAP_CMD23;
 }
-#endif
-
+#endif /* LINUX_MMC_HOST_H */