Documentation: KVM: make corrections to ppc-pv.rst

Documentation: KVM: make corrections to ppc-pv.rst

Correct the path of a header file.
Change "guest to ... guest" to "guest to ... host" in one place.
Hyphenate "32-bit" systems.
Add a comma at one parenthetical phrase.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: kvm@vger.kernel.org
Cc: Alexander Graf <agraf@suse.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230612030810.23376-4-rdunlap@infradead.org