Staging: android: ion: duplicated clearing of sg_table

Because sg_table is cleared in sg_alloc_table via memset we don't need to use
kzalloc to allocate sg_table.

Signed-off-by: Gioh Kim <gioh.kim@lge.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>