net/mlx5: Fix FW tracer timestamp calculation

net/mlx5: Fix FW tracer timestamp calculation

[ Upstream commit 7bec9374e292eed8680c62580e3d7b3347891201 ]

Fix a bug in calculation of FW tracer timestamp. Decreasing one in the
calculation should effect only bits 52_7 and not effect bits 6_0 of the
timestamp, otherwise bits 6_0 are always set in this calculation.

Fixes: 4b1adef39da3 ("net/mlx5: FW tracer, parse traces and kernel tracing support")
Signed-off-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Feras Daoud <ferasda@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>