x86/mm: Use encrypted access of boot related data with SEV

When Secure Encrypted Virtualization (SEV) is active, boot data (such as
EFI related data, setup data) is encrypted and needs to be accessed as
such when mapped. Update the architecture override in early_memremap to
keep the encryption attribute when mapping this data.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Tested-by: Borislav Petkov <bp@suse.de>
Cc: Laura Abbott <labbott@redhat.com>
Cc: kvm@vger.kernel.org
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Link: https://lkml.kernel.org/r/20171020143059.3291-6-brijesh.singh@amd.com