remoteproc: Adapt coredump to generate correct elf type

remoteproc: Adapt coredump to generate correct elf type

Now that remoteproc can load an elf64, coredump elf class should be
the same as the loaded elf class. In order to do that, add a
elf_class field to rproc with default values. If an elf is loaded
successfully, this field will be updated with the loaded elf class.
Then, the coredump core code has been modified to use the generic elf
macro in order to create an elf file with correct class.

Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Clement Leger <cleger@kalray.eu>
Link: https://lore.kernel.org/r/20200302093902.27849-9-cleger@kalray.eu
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>