sparc64: Fix prototype warning for vmemmap_free

Fix the following warning:
arch/sparc/mm/init_64.c:2644:6: warning: no previous prototype for ‘vmemmap_free’

The function vmemmap_free() is only used for systems with
CONFIG_MEMORY_HOTPLUG defined - and sparc64 do not support this.
Drop the empty function as it has no users.

Signed-off-by: Sam Ravnborg <[email protected]>
Cc: Andreas Larsson <[email protected]>
Cc: David S. Miller <[email protected]>
Reviewed-by: Andreas Larsson <[email protected]>
Tested-by: Andreas Larsson <[email protected]>
Acked-by: Arnd Bergmann <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Andreas Larsson <[email protected]>

Author: sravnborg

arch/sparc/mm/init_64.c

@@ -2640,11 +2640,6 @@ int __meminit vmemmap_populate(unsigned long vstart, unsigned long vend,
 
 	return 0;
 }
-
-void vmemmap_free(unsigned long start, unsigned long end,
-		struct vmem_altmap *altmap)
-{
-}
 #endif /* CONFIG_SPARSEMEM_VMEMMAP */
 
 /* These are actually filled in at boot time by sun4{u,v}_pgprot_init() */