x86/EFI: warn about r/o sections requiring relocations

x86/EFI: warn about r/o sections requiring relocations

EFI implementations may write-protect r/o sections, but we need to
apply relocations. Eliminate the one present case of a r/o section
with relocations (.init.text, which is now being combined with
.init.data into just .init).

Also correct a few other format strings (to account for the possibly
missing NUL in section names) in mkreloc.c.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>