x86/platform/intel-mid: Enable 64-bit build

Intel Tangier SoC is known to have 64-bit dual core CPU. Enable
64-bit build for it.

The kernel has been tested on Intel Edison board:

	Linux buildroot 4.4.0-next-20160115+ #25 SMP Fri Jan 15 22:03:19 EET 2016 x86_64 GNU/Linux

	processor       : 0
	vendor_id       : GenuineIntel
	cpu family      : 6
	model           : 74
	model name      : Genuine Intel(R) CPU   4000  @  500MHz
	stepping        : 8
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1452888668-147116-1-git-send-email-andriy.shevchenko@linux.intel.comSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/Kconfig

@@ -495,11 +495,10 @@ config X86_INTEL_CE
 
 config X86_INTEL_MID
 	bool "Intel MID platform support"
-	depends on X86_32
 	depends on X86_EXTENDED_PLATFORM
 	depends on X86_PLATFORM_DEVICES
 	depends on PCI
-	depends on PCI_GOANY
+	depends on X86_64 || (PCI_GOANY && X86_32)
 	depends on X86_IO_APIC
 	select SFI
 	select I2C

arch/x86/kernel/head64.c

@@ -192,5 +192,13 @@ void __init x86_64_start_reservations(char *real_mode_data)
 
 	reserve_ebda_region();
 
+	switch (boot_params.hdr.hardware_subarch) {
+	case X86_SUBARCH_INTEL_MID:
+		x86_intel_mid_early_setup();
+		break;
+	default:
+		break;
+	}
+
 	start_kernel();
 }