OvmfPkg/BaseMemEncryptSevLib: remove Flush parameter

BZ: https://bugzilla.tianocore.org/show_bug.cgi?id=3275

The Flush parameter is used to provide a hint whether the specified range
is Mmio address. Now that we have a dedicated helper to clear the
memory encryption mask for the Mmio address range, its safe to remove the
Flush parameter from MemEncryptSev{Set,Clear}PageEncMask().

Since the address specified in the MemEncryptSev{Set,Clear}PageEncMask()
points to a system RAM, thus a cache flush is required during the
encryption mask update.

Cc: James Bottomley <jejb@linux.ibm.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Laszlo Ersek <lersek@redhat.com>
Cc: Erdem Aktas <erdemaktas@google.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Message-Id: <20210519181949.6574-14-brijesh.singh@amd.com>

OvmfPkg/IoMmuDxe/AmdSevIoMmu.c

@@ -252,8 +252,7 @@ IoMmuMap (
   Status = MemEncryptSevClearPageEncMask (
              0,
              MapInfo->PlainTextAddress,
-             MapInfo->NumberOfPages,
-             TRUE
+             MapInfo->NumberOfPages
              );
   ASSERT_EFI_ERROR (Status);
   if (EFI_ERROR (Status)) {
@@ -407,8 +406,7 @@ IoMmuUnmapWorker (
   Status = MemEncryptSevSetPageEncMask (
              0,
              MapInfo->PlainTextAddress,
-             MapInfo->NumberOfPages,
-             TRUE
+             MapInfo->NumberOfPages
              );
   ASSERT_EFI_ERROR (Status);
   if (EFI_ERROR (Status)) {