libqos/ahci: Functional register helpers

libqos/ahci: Functional register helpers

Introduce a set of "static inline" register helpers that are intended to
replace the current set of macros with more functional versions that are
better suited to inclusion in libqos than porcelain macros.

As a stopgap measure before eliminating the porcelain macros, define them
to use the new functions defined in the ahci.h header.

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1421698563-6977-13-git-send-email-jsnow@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>