mmc: Rename timeout parameters for clarification

It's quite hard to figure out time units for various function that have
timeout parameters. This leads to possible errors when one forgets to
convert ms to us, for example. Let's rename those parameters
correspondingly to 'timeout_us' and 'timeout_ms' to prevent such issues
further.

While at it, add time units info as comments to struct mmc fields.

This commit doesn't change the behavior, only renames parameters names.
Buildman should report no changes at all.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Peng Fan <peng.fan@nxp.com>
Reviewed-by: Igor Opaniuk <igor.opaniuk@gmail.com>
diff --git a/drivers/mmc/omap_hsmmc.c b/drivers/mmc/omap_hsmmc.c
index 3ea7f4e..bade129 100644
--- a/drivers/mmc/omap_hsmmc.c
+++ b/drivers/mmc/omap_hsmmc.c
@@ -430,7 +430,7 @@
 	writel(ac12, &mmc_base->ac12);
 }
 
-static int omap_hsmmc_wait_dat0(struct udevice *dev, int state, int timeout)
+static int omap_hsmmc_wait_dat0(struct udevice *dev, int state, int timeout_us)
 {
 	int ret = -ETIMEDOUT;
 	u32 con;
@@ -442,8 +442,8 @@
 	con = readl(&mmc_base->con);
 	writel(con | CON_CLKEXTFREE | CON_PADEN, &mmc_base->con);
 
-	timeout = DIV_ROUND_UP(timeout, 10); /* check every 10 us. */
-	while (timeout--)	{
+	timeout_us = DIV_ROUND_UP(timeout_us, 10); /* check every 10 us. */
+	while (timeout_us--) {
 		dat0_high = !!(readl(&mmc_base->pstate) & PSTATE_DLEV_DAT0);
 		if (dat0_high == target_dat0_high) {
 			ret = 0;