libata: allocate ap separately from shost

Don't embed ap inside shost. Allocate it separately and point it back from shosts's hostdata. This makes port allocation more flexible and allows regular ATA and SAS share host alloc/init paths.

Signed-off-by Tejun Heo <[email protected]>

---
 drivers/ata/libata-core.c |   19 ++++++++++++++-----
 include/linux/libata.h    |    2 +-
 2 files changed, 15 insertions(+), 6 deletions(-)