eal/ppc64: use glibc for cpu cycles count
eal/ppc64: use glibc for cpu cycles count

__ppc_get_timebase() reads and returns the current value of the Time
Base Register. It's more efficient as it uses the processor’s time
base facility directly.

DPDK on FreeBSD currently is not supported on Powerpc64, it should
be safe to include the sys/platform/ppc.h.

Signed-off-by: Thinh Tran <9b1b46502f9bb1ca3a99e7681d64f745602acbd7@linux.vnet.ibm.com>
Reviewed-by: David Christensen <9a876b0e626a7e524926f129e2e0ea9c4c104ff4@linux.vnet.ibm.com>

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