remoteproc: Rename rproc_elf_sanity_check for elf32

remoteproc: Rename rproc_elf_sanity_check for elf32

Since this function will be modified to support both elf32 and elf64,
rename the existing one to elf32 (which is the only supported format
at the moment). This will allow not to introduce possible side effect
when adding elf64 support (ie: all backends will still support only
elf32 if not requested explicitely using rproc_elf_sanity_check).

Signed-off-by: Clement Leger <cleger@kalray.eu>
Link: https://lore.kernel.org/r/20200302093902.27849-6-cleger@kalray.eu
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>