[PATCH v4 09/11] x86: use io_remap to access real_mode_data

When 64bit bootloader put real mode data above 4g, We can not access real mode data directly yet. because in arch/x86/kernel/head_64.S, only set ident mapping for 0-1g, and kernel code/data/bss. So need to move early_ioremap_init() calling early from setup_arch() to x86_64_start_kernel(). Also

[PATCH v4 09/11] x86: use io_remap to access real_mode_data

When 64bit bootloader put real mode data above 4g, We can not access real mode data directly yet. because in arch/x86/kernel/head_64.S, only set ident mapping for 0-1g, and kernel code/data/bss. So need to move early_ioremap_init() calling early from setup_arch() to x86_64_start_kernel(). Also