Revert "x86/pvh: Call C code via the kernel virtual mapping"

This reverts commit 83d123e2 which is
commit e8fbc0d9 upstream.

It causes boot failures of domU guests, and should be reverted.

Cc: Jason Andryuk <jason.andryuk@amd.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Sasha Levin <sashal@kernel.org>
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Link: https://lore.kernel.org/r/Z1l6XbHP6BTTZSwr@mail-itl


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>