ata: libata-sata: improve sysfs description for ATA_LPM_UNKNOWN

Currently, both ATA_LPM_UNKNOWN (0) and ATA_LPM_MAX_POWER (1) displays
as "max_performance" in sysfs.

This is quite misleading as they are not the same.

For ATA_LPM_UNKNOWN, ata_eh_set_lpm() will not be called at all,
leaving the configuration in unknown state.
For ATA_LPM_MAX_POWER, ata_eh_set_lpm() is called, and setting the
policy to ATA_LPM_MAX_POWER.

This also matches the description of the SATA_MOBILE_LPM_POLICY Kconfig:
0 => Keep firmware settings
1 => Maximum performance

Thus, update the sysfs description for ATA_LPM_UNKNOWN to match reality.

While at it, update libata.h to mention that the ascii descriptions
are in libata-sata.c and not in libata-scsi.c.
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Niklas Cassel <cassel@kernel.org>

drivers/ata/libata-sata.c

@@ -784,7 +784,7 @@ bool sata_lpm_ignore_phy_events(struct ata_link *link)
 EXPORT_SYMBOL_GPL(sata_lpm_ignore_phy_events);
 
 static const char *ata_lpm_policy_names[] = {
-	[ATA_LPM_UNKNOWN]		= "max_performance",
+	[ATA_LPM_UNKNOWN]		= "keep_firmware_settings",
 	[ATA_LPM_MAX_POWER]		= "max_performance",
 	[ATA_LPM_MED_POWER]		= "medium_power",
 	[ATA_LPM_MED_POWER_WITH_DIPM]	= "med_power_with_dipm",

include/linux/libata.h

@@ -471,7 +471,7 @@ enum ata_completion_errors {
 
 /*
  * Link power management policy: If you alter this, you also need to
- * alter libata-scsi.c (for the ascii descriptions)
+ * alter libata-sata.c (for the ascii descriptions)
  */
 enum ata_lpm_policy {
 	ATA_LPM_UNKNOWN,