Fix IA64 discontig.c Section mismatch warnings.

When CONFIG_SPARSEMEM=y and CONFIG_MEMORY_HOTPLUG=y, the functions
computer_pernodesize() and scatter_node_data() should not be marked as
__meminit because they are needed after init, on any memory hotplug
event.  Also, early_nr_cpus_node() is called by compute_pernodesize(),
so early_nr_cpus_node() cannot be __meminit either.

  WARNING: modpost: vmlinux.o(.text.unlikely+0x1612): Section mismatch in reference from the function arch_alloc_nodedata() to the function .meminit.text:compute_pernodesize()
  The function arch_alloc_nodedata() references the function __meminit compute_pernodesize().
  This is often because arch_alloc_nodedata lacks a __meminit annotation or the annotation of compute_pernodesize is wrong.

  WARNING: modpost: vmlinux.o(.text.unlikely+0x1692): Section mismatch in reference from the function arch_refresh_nodedata() to the function .meminit.text:scatter_node_data()
  The function arch_refresh_nodedata() references the function __meminit scatter_node_data().
  This is often because arch_refresh_nodedata lacks a __meminit annotation or the annotation of scatter_node_data is wrong.

  WARNING: modpost: vmlinux.o(.text.unlikely+0x1502): Section mismatch in reference from the function compute_pernodesize() to the function .meminit.text:early_nr_cpus_node()
  The function compute_pernodesize() references the function __meminit early_nr_cpus_node().
  This is often because compute_pernodesize lacks a __meminit annotation or the annotation of early_nr_cpus_node is wrong.

Link: https://lkml.kernel.org/r/20210411001201.3069-1-rdunlap@infradead.orgSigned-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>