Documentation: mips: Update AU1xxx_IDE Kconfig dependencies

IDEDMA_AUTO IDEDMA_PCI_AUTO was removed in commit 120b9cfd ("ide: remove CONFIG_IDEDMA_{ICS,PCI}_AUTO config")
BLK_DEV_IDEDISK was removed in commit 806f80a6 ("ide: add generic ATA/ATAPI disk driver")
BLK_DEV_IDE_AU1XXX_BURSTABLE_ON was removed in commit 8f29e650 ("ide: AU1200 IDE update")
Remove them from documentation

Signed-off-by: Corentin Labbe <clabbe@baylibre.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>