KVM: x86: extend usage of RET_MMIO_PF_* constants

commit 9b8ebbdb74b5ad76b9dfd8b101af17839174b126 upstream.

The x86 MMU if full of code that returns 0 and 1 for retry/emulate.  Use
the existing RET_MMIO_PF_RETRY/RET_MMIO_PF_EMULATE enum, renaming it to
drop the MMIO part.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Backlund <tmb@mageia.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>