OvmfPkg: Update code to be more C11 compliant by using __func__

__FUNCTION__ is a pre-standard extension that gcc and Visual C++ among
others support, while __func__ was standardized in C99.

Since it's more standard, replace __FUNCTION__ with __func__ throughout
OvmfPkg.

Signed-off-by: Rebecca Cran <rebecca@bsdio.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Sunil V L <sunilvl@ventanamicro.com>

OvmfPkg/Library/GenericQemuLoadImageLib/GenericQemuLoadImageLib.c

@@ -201,7 +201,7 @@ QemuLoadKernelImage (
       DEBUG ((
         Status == EFI_NOT_FOUND ? DEBUG_INFO : DEBUG_ERROR,
         "%a: LoadImage(): %r\n",
-        __FUNCTION__,
+        __func__,
         Status
         ));
       return Status;
@@ -279,7 +279,7 @@ QemuLoadKernelImage (
       DEBUG ((
         DEBUG_ERROR,
         "%a: kernel command line is not NUL-terminated\n",
-        __FUNCTION__
+        __func__
         ));
       Status = EFI_PROTOCOL_ERROR;
       goto FreeCommandLine;
@@ -330,7 +330,7 @@ QemuLoadKernelImage (
     DEBUG ((
       DEBUG_INFO,
       "%a: command line: \"%s\"\n",
-      __FUNCTION__,
+      __func__,
       (CHAR16 *)KernelLoadedImage->LoadOptions
       ));
   }