eal: fix C++17 compilation
eal: fix C++17 compilation

Compiling a C++ application that includes directly or indirectly
rte_common.h will cause a warning:

include/rte_common.h:350:37: warning: ISO C++17 does not allow
  ‘register’ storage class specifier [-Wregister]
 rte_combine32ms1b(register uint32_t x)

C++ is pickier than standard C and flags this antique usage.

The register keyword is an old K&R legacy and should be removed
everywhere in DPDK. For now, fix it where it hurts.

Fixes: 08f683174e94 ("eal: add functions for previous power of 2 alignment")
Cc: stable@dpdk.org

Signed-off-by: Stephen Hemminger <06fa905d7f2aaced6dc72e9511c71a2a51e8aead@networkplumber.org>
Acked-by: Bruce Richardson <66b9e8e8fbd5e9f41f91b0af050876182ce9d0e4@intel.com>

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