QcomModulePkg: Add support for AVB2.0 when A/B feature is disabled.

Add support in AVB when multislot is disabled.
Remove explicit checks, support handling alternate
slot only when multislot is enabled.
Support loading of recovery image when multislot is
disabled and booting into recovery mode.

Acked-by: Barani Muthukumaran <bmuthuku@qti.qualcomm.com>
Change-Id: I9aa07ec63cd5767c79555a7b93f778ca13f734d6
4 files changed