Fix BIOS enum attribute to allow updating BaseBIOSTable
Fix BIOS enum attribute to allow updating BaseBIOSTable

- Old function: BaseBIOSTable is not allowed to be updated if there
  is no D-Bus backend.

- New function: Both with D-Bus backend and without D-Bus backend,
  BaseBIOSTable should be updated.

Tested:
- Old function:
  busctl set-property xyz.openbmc_project.BIOSConfigManager /xyz/openbmc_project/bios_config/manager xyz.openbmc_project.BIOSConfig.Manager PendingAttributes a{s\(sv\)} 1 "pvm_default_os_type" "xyz.openbmc_project.BIOSConfig.Manager.AttributeType.Enumeration" s "Linux"

  busctl call  xyz.openbmc_project.BIOSConfigManager /xyz/openbmc_project/bios_config/manager xyz.openbmc_project.BIOSConfig.Manager GetAttribute s pvm_default_os_type
svv "xyz.openbmc_project.BIOSConfig.Manager.AttributeType.Enumeration" s "AIX" s ""

- New function:
  busctl set-property xyz.openbmc_project.BIOSConfigManager /xyz/openbmc_project/bios_config/manager xyz.openbmc_project.BIOSConfig.Manager PendingAttributes a{s\(sv\)} 1 "pvm_default_os_type" "xyz.openbmc_project.BIOSConfig.Manager.AttributeType.Enumeration" s "Linux"

  busctl call  xyz.openbmc_project.BIOSConfigManager /xyz/openbmc_project/bios_config/manager xyz.openbmc_project.BIOSConfig.Manager GetAttribute s pvm_default_os_type
svv "xyz.openbmc_project.BIOSConfig.Manager.AttributeType.Enumeration" s "Linux" s ""

Signed-off-by: George Liu <f124e69123cb985598dfa856ba74cb3263194267@inspur.com>
Change-Id: I0f0186583448839f3f8cb4765e81fc84bca596b2

openbmc/pldm,openbmc/pldm,openbmc/pldm