kexec_file, riscv: print out debugging message if required

kexec_file, riscv: print out debugging message if required

Then when specifying '-d' for kexec_file_load interface, loaded locations
of kernel/initrd/cmdline etc can be printed out to help debug.

Here replace pr_debug() with the newly added kexec_dprintk() in kexec_file
loading related codes.

And also replace pr_notice() with kexec_dprintk() in elf_kexec_load()
because loaded location of purgatory and device tree are only printed out
for debugging, it doesn't make sense to always print them out.

And also remove kexec_image_info() because the content has been printed
out in generic code.

Link: https://lkml.kernel.org/r/20231213055747.61826-6-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Conor Dooley <conor@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>