OvmfPkg/Bhyve: don't exit early if RSDP is not found in memory

If OVMF fails to find the RSDP in memory, it should fall back installing
the statically provided ACPI tables.

Signed-off-by: Corvin Köhne <corvink@FreeBSD.org>

PR: 273560
Reviewed by: madpilot, manu
Approved by: manu
Fixes: 8097dda40a03b8a27a1edf1f31a8af0455a52baf ("sysutils/edk2: update to 202308")
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D41769