opcodes: microblaze: Add new bit-field instructions

This patches adds new bsefi and bsifi instructions.
BSEFI- The instruction shall extract a bit field from a
register and place it right-adjusted in the destination register.
The other bits in the destination register shall be set to zero.
BSIFI- The instruction shall insert a right-adjusted bit field
from a register at another position in the destination register.
The rest of the bits in the destination register shall be unchanged.

Further documentation of these instructions can be found here:
https://docs.xilinx.com/v/u/en-US/ug984-vivado-microblaze-ref

This patch has been tested for years of AMD Xilinx Yocto
releases as part of the following patch set:

https://github.com/Xilinx/meta-xilinx/tree/master/meta-microblaze/recipes-devtools/binutils/binutils



Signed-off-by: nagaraju <nagaraju.mekala@amd.com>
Signed-off-by: Ibai Erkiaga <ibai.erkiaga-elorza@amd.com>
Signed-off-by: Neal Frager <neal.frager@amd.com>
Signed-off-by: Michael J. Eager <eager@eagercon.com>