drivers: mmc: omap_hsmmc: Fix conversion of address to a pointer

drivers: mmc: omap_hsmmc: Fix conversion of address to a pointer

omap_hsmmc driver directly typecasts fdt_addr_t to a pointer.
This is not strictly correct, as it gives a build warning when
fdt_addr_t is u64. So, use map_physmem for a proper typecasts.

This is inspired by commit 167efe01bc5a9 ("dm: ns16550: Use an address
instead of a pointer for the uart base")

drivers/mmc/omap_hsmmc.c: In function ‘omap_hsmmc_ofdata_to_platdata’:
drivers/mmc/omap_hsmmc.c:776:20: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast]
  priv->base_addr = (struct hsmmc *)dev_get_addr(dev);
                      ^

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>