examples/performance-thread: fix compilation on Suse 11 SP2

examples/performance-thread: fix compilation on Suse 11 SP2

Fixes following compilation error, using uint64_t type,
instead of int128_t unnecessarily:

In file included from ./common/lthread.c:82:0:
./common/lthread_timer.h: In function ‘_ns_to_clks’:
./common/lthread_timer.h:49:20: error: expected ‘=’, ‘,’, ‘;’,
 ‘asm’ or ‘__attribute__’ before ‘clkns’
compilation terminated due to -Wfatal-errors.

Fixes: 116819b9ed0d ("examples/performance-thread: add lthread subsystem")
Cc: stable@dpdk.org
Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>