scsi: ufs: fix Auto-Hibern8 error detection

scsi: ufs: fix Auto-Hibern8 error detection

Auto-Hibern8 may be disabled by some vendors or sysfs in runtime even if
Auto-Hibern8 capability is supported by host. If Auto-Hibern8 capability is
supported by host but not actually enabled, Auto-Hibern8 error shall not
happen.

To fix this, provide a way to detect if Auto-Hibern8 is actually enabled
first, and bypass Auto-Hibern8 disabling case in
ufshcd_is_auto_hibern8_error().

Fixes: 821744403913 ("scsi: ufs: Add error-handling of Auto-Hibernate")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20200129105251.12466-4-stanley.chu@mediatek.com
Reviewed-by: Bean Huo <beanhuo@micron.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>