Fix the following compilation errors/warnings:

drivers/ata/sata_dwc_460ex.c:43:1: warning: "DRV_NAME" redefined
In file included from drivers/ata/sata_dwc_460ex.c:38:
drivers/ata/libata.h:31:1: warning: this is the location of the previous
definition
drivers/ata/sata_dwc_460ex.c:44:1: warning: "DRV_VERSION" redefined
drivers/ata/libata.h:32:1: warning: this is the location of the previous
definition
drivers/ata/sata_dwc_460ex.c: In function `sata_dwc_exec_command_by_tag':
drivers/ata/sata_dwc_460ex.c:1356: warning: passing argument 1 of
`ata_get_cmd_descript' makes integer from pointer without a cast
drivers/ata/sata_dwc_460ex.c: In function `sata_dwc_qc_issue':
drivers/ata/sata_dwc_460ex.c:1476: warning: `err' is used uninitialized in this
function
drivers/ata/sata_dwc_460ex.c:1465: note: `err' was declared here
drivers/ata/sata_dwc_460ex.c: In function `sata_dwc_qc_issue':
drivers/ata/sata_dwc_460ex.c:1493: warning: passing argument 1 of
`ata_get_cmd_descript' makes integer from pointer without a cast
drivers/ata/sata_dwc_460ex.c: In function `sata_dwc_qc_prep':
drivers/ata/sata_dwc_460ex.c:1537: error: `tag' undeclared (first use in this
function)
drivers/ata/sata_dwc_460ex.c:1537: error: (Each undeclared identifier is
reported only once
drivers/ata/sata_dwc_460ex.c:1537: error: for each function it appears in.)

NB: error only happens if DEBUG_NCQ macro is defined...

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>