libata: Use integer return value for atapi_command_packet_set

The function returns type of ATAPI drives so it should return integer value.
The commit 4dce8ba9 (libata: Use 'bool' return value for ata_id_XXX) since
v2.6.39 changed the type of return value from int to bool, the change would
cause all of the ATAPI class drives to be treated as TYPE_TAPE and the
max_sectors of the drives to be set to 65535 because of the commit
f8d8e579(libata: increase 128 KB / cmd limit for ATAPI tape drives), for the
function would return true for all ATAPI class drives and the TYPE_TAPE is
defined as 0x01.

Cc: stable@vger.kernel.org
Signed-off-by: Shan Hai <shan.hai@windriver.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>