ata: libata-eh: Fix link state check for IDE/PATA ports

ata: libata-eh: Fix link state check for IDE/PATA ports

Commit 4371fe1ba400 ("ata: libata-eh: Avoid unnecessary resets when
revalidating devices") replaced the call to ata_phys_link_offline() in
ata_eh_revalidate_and_attach() with the new function
ata_eh_link_established() which relaxes the checks on a device link
state to account for low power mode transitions. However, this change
assumed that the device port has a valid scr_read method to obtain the
SStatus register for the port. This is not always the case, especially
with older IDE/PATA adapters (e.g. PATA/IDE devices emulated with QEMU).
For such adapter, ata_eh_link_established() will always return false,
causing ata_eh_revalidate_and_attach() to go into its error path and
ultimately to the device being disabled.

Avoid this by restoring the previous behavior, which is to assume that
the link is online if reading the port SStatus register fails.

While at it, also fix the spelling of SStatus in the comment describing
the function ata_eh_link_established().

Reported-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Fixes: 4371fe1ba400 ("ata: libata-eh: Avoid unnecessary resets when revalidating devices")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Tested-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Reviewed-by: Niklas Cassel <cassel@kernel.org>