powerpc/fixmap: don't clear fixmap area in paging_init()

fixmap is intended to map things permanently like the IMMR region on
FSL SOC (8xx, 83xx, ...), so don't clear it when initialising paging()

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/41c99bc06394a6bc2888631cb98a3ed2ae281ddb.1568295907.git.christophe.leroy@c-s.fr

arch/powerpc/mm/mem.c

@@ -237,14 +237,6 @@ void __init paging_init(void)
 	unsigned long long total_ram = memblock_phys_mem_size();
 	phys_addr_t top_of_ram = memblock_end_of_DRAM();
 
-#ifdef CONFIG_PPC32
-	unsigned long v = __fix_to_virt(__end_of_fixed_addresses - 1);
-	unsigned long end = __fix_to_virt(FIX_HOLE);
-
-	for (; v < end; v += PAGE_SIZE)
-		map_kernel_page(v, 0, __pgprot(0)); /* XXX gross */
-#endif
-
 #ifdef CONFIG_HIGHMEM
 	map_kernel_page(PKMAP_BASE, 0, __pgprot(0));	/* XXX gross */
 	pkmap_page_table = virt_to_kpte(PKMAP_BASE);