linux-wandboard

libata: Separate libata.ko build from individual driver builds

Since some SAS drivers need libata, we can no longer use the rule that
auto-builds libata.ko as needed.  We must instead depend on Kconfig to
determine when to build the library kernel module.

Noticed by Brian King @ IBM.

Signed-off-by: Jeff Garzik <jeff@garzik.org>