config/ppc: fix native build with GCC 4.8.5 on RHEL 7
config/ppc: fix native build with GCC 4.8.5 on RHEL 7

The POWER meson.build file incorrectly checks if the detected CPU is
"greater than" POWER8 when it should actually test for "greater than or
equal to" POWER8.  Fixed the comparison operator.

Bugzilla ID: 875
Fixes: 750196880843 ("config/ppc: select instruction set for IBM Power10")

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

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