microblaze: Get module loading working

New reloc type R_MICROBLAZE_32_PCREL_LO requires a null handler (no work to do).

Remove legacy hack for broken linker pre gcc-4.1.1, that required us to extract
an offset from the code, add it to the addend, then rewrite the instruction.

Fixup the invalid reloc type error output.

Boot tested with the xilinx_emaclite ethernet driver.

Signed-off-by: John Williams <john.williams@petalogix.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>