ata_piix.c:piix_init_one() must be __devinit

This patch fixes the following section mismatches:

<--  snip  -->

...
WARNING: drivers/ata/built-in.o(.text+0x15072): Section mismatch in reference from the function piix_init_one() to the function .devinit.text:piix_init_sata_map()
WARNING: drivers/ata/built-in.o(.text+0x150dd): Section mismatch in reference from the function piix_init_one() to the function .devinit.text:piix_init_pcs()
WARNING: drivers/ata/built-in.o(.text+0x150e5): Section mismatch in reference from the function piix_init_one() to the function .devinit.text:piix_init_sidpr()
WARNING: drivers/ata/built-in.o(.text+0x15107): Section mismatch in reference from the function piix_init_one() to the function .devinit.text:piix_check_450nx_errata()
...

<--  snip  -->

Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>