CHROMIUM: libata: remove warning

CHROMIUM: libata: remove warning

drivers/ata/libata-core.c:5376:2: warning: assignment from incompatible pointer type [enabled by default]
drivers/ata/libata-core.c:5577:2: warning: assignment from incompatible pointer type [enabled by default]

BUG=chromium-os:34287
TEST=none

Change-Id: Ic0af73ba8fbc4aefb5895d00ec0bc853fcbec192
Signed-off-by: Olof Johansson <olofj@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/32834
Reviewed-by: Sonny Rao <sonnyrao@chromium.org>
Reviewed-by: Derek Basehore <dbasehore@chromium.org>