efi: Rename the media device

The current name of 'efi_media' is annoying in that it must be given
with 'bootflow scan'. We would prefer to use 'bootflow scan efi', for
example.

Rename the driver to 'efi'.

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/block/efi-media-uclass.c

@@ -9,6 +9,6 @@
 
 UCLASS_DRIVER(efi_media) = {
 	.id		= UCLASS_EFI_MEDIA,
-	.name		= "efi_media",
+	.name		= "efi",
 	.flags		= DM_UC_FLAG_SEQ_ALIAS,
 };