arm64: relocate-rela: Add support for ld.lld

arm64: relocate-rela: Add support for ld.lld

Cap end of relocations by the binary size.

Linkers like to insert some auxiliary sections between .rela.dyn and
.bss_start. These sections don't make their way to the final binary, but
reloc_rela still tries to relocate them, resulting in attempted read
past the end of file.

When linking U-Boot with ld.lld, the STATIC_RELA feature (enabled by
default on arm64) breaks the build. After this patch, U-Boot can be
linked successfully with and without CONFIG_STATIC_RELA.

Originally-from: Elena Petrova <lenaptr@google.com>
Signed-off-by: Alistair Delva <adelva@google.com>
Cc: David Brazdil <dbrazdil@google.com>
Cc: Scott Wood <scottwood@freescale.com>
Cc: Tom Rini <trini@konsulko.com>