bnx2x: Set NETIF_F_HIGHDMA unconditionally

Current driver implementation incorrectly sets the flag only if 64-bit
DMA mask succeeded.

Signed-off-by: Merav Sicron <meravs@broadcom.com>
Signed-off-by: Yuval Mintz <yuvalmin@broadcom.com>
Signed-off-by: Ariel Elior <ariele@broadcom.com>
Signed-off-by: Eilon Greenstein <eilong@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>