hexagon: drop empty and unused free_initrd_mem

hexagon never reserves or initializes initrd and the only mention of it is
the empty free_initrd_mem() function.

As we have a generic implementation of free_initrd_mem(), there is no need
to define an empty stub for the hexagon implementation and it can be
dropped.

Link: http://lkml.kernel.org/r/1565858133-25852-1-git-send-email-rppt@linux.ibm.comSigned-off-by: Mike Rapoport <rppt@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: Richard Kuo <rkuo@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/hexagon/mm/init.c

@@ -71,19 +71,6 @@ void __init mem_init(void)
 	init_mm.context.ptbase = __pa(init_mm.pgd);
 }
 
-/*
- * free_initrd_mem - frees...  initrd memory.
- * @start - start of init memory
- * @end - end of init memory
- *
- * Apparently has to be passed the address of the initrd memory.
- *
- * Wrapped by #ifdef CONFIG_BLKDEV_INITRD
- */
-void free_initrd_mem(unsigned long start, unsigned long end)
-{
-}
-
 void sync_icache_dcache(pte_t pte)
 {
 	unsigned long addr;