mmc: omap_hsmmc: Don't expect MMC1 to always have vmmc supply

MMC1 is not the only instance that can be used/wired for SD.
So remove this assumption from the driver.

Now that all the mmc id based usage is removed, get rid of all the DEVID
defines and also the 'id' field from the omap_hsmmc_host structure.

Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Tested-by: Venkatraman S <svenkatr@ti.com>
Tested-by: Balaji T K <balajitk@ti.com>
Signed-off-by: Chris Ball <cjb@laptop.org>