In preparation for 64bit mode remove all the _4 from the function and
macro names, rename val4 to val, and m4 to md.

No functional change.

MFC after:	2 weeks
Rather than using a constant use sizeof(val) allowing for the length
to automatically change as we switch between 32/64bit.

MFC after:	2 weeks
Allow switching between 32bit and 64bit bus width data access at compile
time by setting NF10BMAC_64BIT and using a REGWTYPE #define to set correct
variable and return value widths.

Adjust comments to indicate the 32 or 64bit register widths.

MFC after:	2 weeks
Add support for emulating the move instruction: "mov r/m8, imm8".

Reviewed by:	neel
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