Introduce opt_netfpga.h and allow setting NF10BMAC_64BIT from mips kernel

configs.  Switch the BERI_NETFPGA_MDROOT to 64bit by default.

Give we have working interrupts also cleanup the extra polling CFLAGS from
the module Makefile.

MFC after:	2 weeks

sys/conf/options.mips

@@ -90,6 +90,11 @@ OCTEON_BOARD_CAPK_0100ND	opt_cvmx.h
 #
 BERI_LARGE_TLB			opt_global.h
 
+#
+# Options that control the NetFPGA-10G Embedded CPU Ethernet Core.
+#
+NF10BMAC_64BIT			opt_netfpga.h
+
 #
 # Options that control the Atheros SoC peripherals
 #

sys/dev/netfpga10g/nf10bmac/if_nf10bmac.c

@@ -40,6 +40,7 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_device_polling.h"
+#include "opt_netfpga.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>

sys/mips/conf/BERI_NETFPGA_MDROOT

@@ -23,6 +23,7 @@ device		bpf
 
 options 	DEVICE_POLLING
 device		netfpga10g_nf10bmac
+options 	NF10BMAC_64BIT
 
 #
 # This kernel configuration uses an embedded memory root file system.

sys/modules/netfpga10g/nf10bmac/Makefile

@@ -6,11 +6,10 @@ KMOD=	if_nf10bmac
 SRCS=	if_nf10bmac.c
 SRCS+=	device_if.h bus_if.h pci_if.h
 SRCS+=	opt_device_polling.h
+SRCS+=	opt_netfpga.h
 
 .if ${MACHINE_CPUARCH} == "mips"
 SRCS+=	if_nf10bmac_fdt.c ofw_bus_if.h
 .endif
 
-CFLAGS+=	-DDEVICE_POLLING
-
 .include <bsd.kmod.mk>