lpm/x86: move SSE implementation to be architecture agnostic

lpm/x86: move SSE implementation to be architecture agnostic

-Used architecture agnostic xmm_t to represent 128 bit SIMD variable

-Introduced vect_* API abstraction in app/test to test rte_lpm_lookupx4
API in  architecture agnostic way

-Moved rte_lpm_lookupx4 SSE implementation to architecture specific
rte_lpm_sse.h file to accommodate new rte_lpm_lookupx4 implementation
for a different architecture.

Signed-off-by: Jerin Jacob <jerin.jacob@caviumnetworks.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>