OvmfPkg/PeilessStartupLib: Delete TdxValidateCfv

OvmfPkg/PeilessStartupLib: Delete TdxValidateCfv

TdxValidateCfv is used to validate the integrity of FlashNvVarStore
(PcdOvmfFlashNvStorageVariableBase) and it is not Tdx specific.
So it will be moved to PlatformInitLib and be renamed to
PlatformValidateNvVarStore in the following patch. And it will be called
before EmuVaribleNvStore is initialized with the content in
FlashNvVarStore.

Cc: Erdem Aktas <erdemaktas@google.com>
Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Min Xu <min.m.xu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>