Revert "ARM: 7098/1: kdump: copy kernel relocation code at the kexec prepare stage"

This reverts commit 2b034922af2caa19df86f0c502e76cb6f6e910f9.

Will Deacon reports:

This is causing kexec to fail.

The symptoms are that the .init.text section is not loaded as part of the
new kernel image, so when we try to do the SMP/UP fixups we hit a whole sea
of poison left there by the previous kernel.

So my guess is that machine_kexec_prepare *is* too early for preparing the
reboot_code_buffer and, unless anybody has a good reason not to, I'd like to
revert the patch causing these problems.

Reported-by: Will Deacon <will.deacon@arm.com>