ata: libata-core: do not retry reading the log on timeout

ata_read_log_page() first tries to read the log using READ LOG DMA EXT.
If that fails it will instead try to read the log using READ LOG EXT.

ata_exec_internal_sg() is synchronous, so it will wait for the command to
finish. If we actually got an error back from the device, it is correct
to retry. However, if the command timed out, ata_exec_internal_sg() will
freeze the port.

There is no point in retrying if the port is frozen, as
ata_exec_internal_sg() will return AC_ERR_SYSTEM on a frozen port,
without ever sending the command down to the drive.

Therefore, avoid retrying if the first command froze the port, as that
will result in a misleading AC_ERR_SYSTEM error print, instead of printing
the error that actually caused the port to be frozen (AC_ERR_TIMEOUT).

Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>