mmc: Split mmc struct, rework mmc initialization (v2)

The way that struct mmc was implemented was a bit of a mess;
configuration and internal state all jumbled up in a single structure.

On top of that the way initialization is done with mmc_register leads
to a lot of duplicated code in drivers.

Typically the initialization got something like this in every driver.

	struct mmc *mmc = malloc(sizeof(struct mmc));
	memset(mmc, 0, sizeof(struct mmc);
	/* fill in fields of mmc struct */
	/* store private data pointer */
	mmc_register(mmc);

By using the new mmc_create call one just passes an mmc config struct
and an optional private data pointer like this:

	struct mmc = mmc_create(&cfg, priv);

All in tree drivers have been updated to the new form, and expect
mmc_register to go away before long.

Changes since v1:

* Use calloc instead of manually calling memset.
* Mark mmc_register as deprecated.

Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
diff --git a/arch/arm/include/asm/arch-davinci/sdmmc_defs.h b/arch/arm/include/asm/arch-davinci/sdmmc_defs.h
index 3e9e606..9aa3f4a 100644
--- a/arch/arm/include/asm/arch-davinci/sdmmc_defs.h
+++ b/arch/arm/include/asm/arch-davinci/sdmmc_defs.h
@@ -151,6 +151,7 @@
 	uint host_caps;		/* Host capabilities */
 	uint voltages;		/* Host supported voltages */
 	uint version;		/* MMC Controller version */
+	struct mmc_config cfg;
 };
 
 enum {