x86/efi: Test for EFI_MEMMAP functionality when iterating EFI memmap

Both efi_find_mirror() and efi_fake_memmap() really want to know
whether the EFI memory map is available, not just whether the machine
was booted using EFI. efi_fake_memmap() even has a check for
EFI_MEMMAP at the start of the function.

Since we've already got other code that has this dependency, merge
everything under one if() conditional, and remove the now superfluous
check from efi_fake_memmap().

Tested-by: Dave Young <dyoung@redhat.com> [kexec/kdump]
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> [arm]
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Taku Izumi <izumi.taku@jp.fujitsu.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>

arch/x86/kernel/setup.c

@@ -1096,19 +1096,18 @@ void __init setup_arch(char **cmdline_p)
 	memblock_set_current_limit(ISA_END_ADDRESS);
 	memblock_x86_fill();
 
-	if (efi_enabled(EFI_BOOT)) {
+	reserve_bios_regions();
+
+	if (efi_enabled(EFI_MEMMAP)) {
 		efi_fake_memmap();
 		efi_find_mirror();
-	}
-
-	reserve_bios_regions();
 
-	/*
-	 * The EFI specification says that boot service code won't be called
-	 * after ExitBootServices(). This is, in fact, a lie.
-	 */
-	if (efi_enabled(EFI_MEMMAP))
+		/*
+		 * The EFI specification says that boot service code won't be
+		 * called after ExitBootServices(). This is, in fact, a lie.
+		 */
 		efi_reserve_boot_services();
+	}
 
 	/* preallocate 4k for mptable mpc */
 	early_reserve_e820_mpc_new();

drivers/firmware/efi/fake_mem.c

@@ -64,7 +64,7 @@ void __init efi_fake_memmap(void)
 	void *old, *new;
 	int i;
 
-	if (!nr_fake_mem || !efi_enabled(EFI_MEMMAP))
+	if (!nr_fake_mem)
 		return;
 
 	/* count up the number of EFI memory descriptor */