ata: ahci: Rename CONFIG_SATA_LPM_POLICY configuration item back

CONFIG_SATA_LPM_MOBILE_POLICY was renamed to CONFIG_SATA_LPM_POLICY in
commit 4dd4d3de

 ("ata: ahci: Rename CONFIG_SATA_LPM_MOBILE_POLICY
configuration item").

This can potentially cause problems as users would invisibly lose
configuration policy defaults when they built the new kernel. To
avoid such problems, switch back to the old name (even if it's wrong).

Suggested-by: Christoph Hellwig <hch@infradead.org>
Suggested-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>