x86/kaslr: Fix build warning in KASLR code in boot stub

x86/kaslr: Fix build warning in KASLR code in boot stub

lib/kaslr.c is used by both the main kernel and the boot stub. It
includes asm/io.h which is supposed to be used in the main kernel. It
leads to build warnings like this with clang 13:

  warning: implicit declaration of function 'outl' is invalid in C99 [-Wimplicit-function-declaration]

Replace <asm/io.h> with <asm/shared/io.h> which is suitable for both
cases.

Fixes: 1e8f93e18379 ("x86: Consolidate port I/O helpers")
Reported-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220410200025.3stf4jjvwfe5oxew@box.shutemov.name