mm/cma: report base address of single range correctly

The cma_declare_contiguous_nid code was refactored by commit c009da42
("mm, cma: support multiple contiguous ranges, if requested"), so that it
could use an internal function to attempt a single range area first, and
then try a multi-range one.

However, that meant that the actual base address used for the !fixed case
(base == 0) wasn't available one level up to be printed in the
informational message, and it would always end up printing a base address
of 0 in the boot message.

Make the internal function take a phys_addr_t pointer to the base address,
so that the value is available to the caller.

[fvdl@google.com: v2]
  Link: https://lkml.kernel.org/r/20250408164000.3215690-1-fvdl@google.com
Link: https://lkml.kernel.org/r/20250407165435.2567898-1-fvdl@google.com


Fixes: c009da42 ("mm, cma: support multiple contiguous ranges, if requested")
Signed-off-by: Frank van der Linden <fvdl@google.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Closes: https://lore.kernel.org/linux-mm/CAMuHMdVWviQ7O9yBFE3f=ev0eVb1CnsQvR6SKtEROBbM6z7g3w@mail.gmail.com/


Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>