microblaze: Use LOAD_OFFSET macro to get correct LMA for all sections

Currently, vmlinux has LMA==VMA for all sections, which is wrong for MMU
kernels.  Previous patches in this series defined the LOAD_OFFSET constant,
now we make use of it in our link script.

Other minor changes in this patch:
	* brace/indenting cleanup of some sections
	* put __fdt_* symbols in their own section, and apply LOAD_OFFSET fixup

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