x86/boot: Parse SRAT table and count immovable memory regions

Parse SRAT for the immovable memory regions and use that information to
control which offset KASLR selects so that it doesn't overlap with any
movable region.

 [ bp:
   - Move struct mem_vector where it is visible so that it builds.
   - Correct comments.
   - Rewrite commit message.
   ]

Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: <caoj.fnst@cn.fujitsu.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: <indou.takao@jp.fujitsu.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: <kasong@redhat.com>
Cc: <keescook@chromium.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: <msys.mizuma@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: x86-ml <x86@kernel.org>
Link: https://lkml.kernel.org/r/20190123110850.12433-7-fanc.fnst@cn.fujitsu.com