ata: sata_via: Use str_up_down() helper in vt6420_prereset()

Remove hard-coded strings by using the str_up_down() helper function.

Signed-off-by: Salah Triki <salah.triki@gmail.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Link: https://lore.kernel.org/r/20250220080757.87278-1-salah.triki@gmail.com


Signed-off-by: Niklas Cassel <cassel@kernel.org>