eal: optimize TSC routines when HPET is disabled
eal: optimize TSC routines when HPET is disabled

Since DPDK has only two timer sources,
Avoid &eal_timer_source memory read and followed
by the switch case statement when
RTE_LIBEAL_USE_HPET is not defined.

Signed-off-by: Jerin Jacob <5bca7d2a432bc0f5422b70b2701a4e4fa32edd00@caviumnetworks.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk