libata: limit post SRST nsect/lbal wait to ~100ms

After SRST, libata used to wait for nsect/lbal to be set to 1/1 for
the slave device.  However, some ATAPI devices don't set nsect/lbal
after SRST and the wait itself isn't too useful as we're gonna wait
for !BSY right after that anyway.

Before reset-seq update, nsect/lbal wait failure used to be ignored
and caused 30sec delay during detection.  After reset-seq, all
timeouts are considered error conditions making libata fail to detect
such ATAPI devices.

This patch limits nsect/lbal wait to around 100ms.  This should give
acceptable behavior to such ATAPI devices while not disturbing the
heavily used code path too much.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>