eal/x86: reduce contention when retrying TSX

eal/x86: reduce contention when retrying TSX

When TSX transactions abort, it is generally worth retrying a number of
times before falling back to the traditional locking path, as the
parallelism benefits from TSX can be worth it when a transaction does
succeed. For cases with multiple threads and high contention rates, it
can be useful to have increasing delays between retry attempts, so as to
avoid having the same threads repeatedly collided.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>