MIPS: add .padding section to linker script

MIPS: add .padding section to linker script

Commit 79fd7e649e287228a1445820a72f7dd33baedb96

    MIPS: always keep all sections in u-boot ELF binary.

    Always keep all sections in u-boot ELF binary. Move all unneeded
    sections after _end to avoid allocating space in the final binary.
    Also remove .deadcode section which is now obsolete.

removed section .deadcode because the original symptoms were not
visible anymore. Unfortuneatly the binutils bug still exists.

The size of .rel.dyn section is often bigger than needed for all
entries. But objcopy only allocates space as much as required for all
reloc entries. Thus there is a gap between the last entry and
__rel_dyn_end in u-boot.bin. If u-boot is booted from RAM (e.g. in
SPL scenarios) that area could contain garbage data which could lead
to CPU exceptions during relocation.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>