ata: add the libata support

add simple libata support in u-boot

---
 drivers/block/Makefile |    1 +
 drivers/block/libata.c |  158 +++++++++++++++++++++++++++++++++++++
 include/libata.h       |  205 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 364 insertions(+), 0 deletions(-)
 create mode 100644 drivers/block/libata.c
 create mode 100644 include/libata.h

index e069969..d63ca2d 100644
@@ -27,6 +27,7 @@ LIB 	:= $(obj)libblock.a
 
 COBJS-y += ahci.o
 COBJS-y += ata_piix.o
+COBJS-$(CONFIG_LIBATA) += libata.o
 COBJS-y += sil680.o
 COBJS-y += sym53c8xx.o
 COBJS-y += systemace.o

1.5.4.rc4