blackfin, m68k: Fix flat_set_persistent() for unsigned long to u32 changes

Several variables had their types changed from unsigned long to u32, but
the arch-specific implementations of flat_set_persistent() weren't
updated, leading to compiler warnings on blackfin and m68k:

    fs/binfmt_flat.c: In function ‘load_flat_file’:
    fs/binfmt_flat.c:799: warning: passing argument 2 of ‘flat_set_persistent’ from incompatible pointer type

Fixes: 468138d7 ("binfmt_flat: flat_{get,put}_addr_from_rp() should be able to fail")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>