x86/boot: Drop erroneous __init annotation from early_set_pages_state()

The kexec code will call set_pages_state() after tearing down all the GHCBs,
which will therefore result in a call to early_set_pages_state().

This means the __init annotation is wrong, and must be dropped.

Fixes: c5c30a37 ("x86/boot: Move startup code out of __head section")
Reported-by: Srikanth Aithal <Srikanth.Aithal@amd.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Srikanth Aithal <Srikanth.Aithal@amd.com>