arm64: mm: Remove unused declaration early_io_map()

Commit bf4b558e ("arm64: add early_ioremap support") removed the
implementation but leave declaration.
Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20240805140038.1366033-1-yuehaibing@huawei.comSigned-off-by: Will Deacon <will@kernel.org>

arch/arm64/include/asm/mmu.h

@@ -63,7 +63,6 @@ static inline bool arm64_kernel_unmapped_at_el0(void)
 extern void arm64_memblock_init(void);
 extern void paging_init(void);
 extern void bootmem_init(void);
-extern void __iomem *early_io_map(phys_addr_t phys, unsigned long virt);
 extern void create_mapping_noalloc(phys_addr_t phys, unsigned long virt,
 				   phys_addr_t size, pgprot_t prot);
 extern void create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,