Revert "x86/kexec: Allocate PGD for x86_64 transition page tables separately"

Revert "x86/kexec: Allocate PGD for x86_64 transition page tables separately"

This reverts commit 6821918f451942aa79759f29677a22f2d4ff4cbe which is
commit 4b5bc2ec9a239bce261ffeafdd63571134102323 upstream.

The patch it relies on is not in the 6.1.y tree, and has been reported
to cause problems, so let's revert it for now.

Reported-by: Eric Hagberg <ehagberg@janestreet.com>
Link: https://lore.kernel.org/r/CAAH4uRBxJ_XvYjCpgYXHqrKSNj6x9pA7X6NBPNTekeQ90DQSJA@mail.gmail.com
Cc: David Woodhouse <dwmw@amazon.co.uk>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>