swiotlb: remove unused swiotlb_alloc_boot()

Nobody uses swiotlb_alloc_boot().

Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Acked-by: Becky Bruce <beckyb@kernel.crashing.org>
diff --git a/lib/swiotlb.c b/lib/swiotlb.c
index bffe6d7..9edfdd4 100644
--- a/lib/swiotlb.c
+++ b/lib/swiotlb.c
@@ -114,11 +114,6 @@
 __setup("swiotlb=", setup_io_tlb_npages);
 /* make io_tlb_overflow tunable too? */
 
-void * __weak __init swiotlb_alloc_boot(size_t size, unsigned long nslabs)
-{
-	return alloc_bootmem_low_pages(size);
-}
-
 void * __weak swiotlb_alloc(unsigned order, unsigned long nslabs)
 {
 	return (void *)__get_free_pages(GFP_DMA | __GFP_NOWARN, order);
@@ -189,7 +184,7 @@
 	/*
 	 * Get IO TLB memory from the low pages
 	 */
-	io_tlb_start = swiotlb_alloc_boot(bytes, io_tlb_nslabs);
+	io_tlb_start = alloc_bootmem_low_pages(bytes);
 	if (!io_tlb_start)
 		panic("Cannot allocate SWIOTLB buffer");
 	io_tlb_end = io_tlb_start + bytes;