cxgb4vf: make single bit signed bitfields unsigned

Single bit signed bitfields don't make a lot of sense, noticed by sparse:
drivers/net/cxgb4vf/t4vf_common.h:135:31: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:136:36: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:137:36: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:138:36: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:139:36: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:140:31: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:141:31: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:142:35: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:143:35: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:154:27: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:155:26: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:156:27: error: dubious one-bit signed bitfield
drivers/net/cxgb4vf/t4vf_common.h:157:26: error: dubious one-bit signed bitfield

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>