staging: ath6kl: Fixing the driver to use modified mmc_host structure

A recent change in the mmc_host structure removed the distinction
between hw and phys segments (58cb50c20fde6059f3f8db4466a1bd4d1fff999c)
Changing the driver to use the modified structure.

Reported-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Vipin Mehta <vmehta@atheros.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>