mmc: core: First step in cleaning up public mmc header files

This is the first step in cleaning up the public mmc header files. In this
change we makes sure each header file builds standalone, as that helps to
resolve dependencies.

While changing this, it also seems reasonable to stop including other
headers from inside a header itself which it don't depend upon.
Additionally, in some cases such dependencies are better resolved by
forward declaring the needed struct.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Reviewed-by: Shawn Lin <shawn.lin@rock-chips.com>

include/linux/mmc/host.h

@@ -10,16 +10,12 @@
 #ifndef LINUX_MMC_HOST_H
 #define LINUX_MMC_HOST_H
 
-#include <linux/leds.h>
-#include <linux/mutex.h>
-#include <linux/timer.h>
 #include <linux/sched.h>
 #include <linux/device.h>
 #include <linux/fault-inject.h>
 
 #include <linux/mmc/core.h>
 #include <linux/mmc/card.h>
-#include <linux/mmc/mmc.h>
 #include <linux/mmc/pm.h>
 
 struct mmc_ios {
@@ -82,6 +78,8 @@ struct mmc_ios {
 	bool enhanced_strobe;			/* hs400es selection */
 };
 
+struct mmc_host;
+
 struct mmc_host_ops {
 	/*
 	 * It is optional for the host to implement pre_req and post_req in
@@ -162,9 +160,6 @@ struct mmc_host_ops {
 				  unsigned int direction, int blk_size);
 };
 
-struct mmc_card;
-struct device;
-
 struct mmc_async_req {
 	/* active mmc request */
 	struct mmc_request	*mrq;