x86/efistub: Fix PCI ROM preservation in mixed mode

preserve_pci_rom_image() was accessing the romsize field in
efi_pci_io_protocol_t directly instead of using the efi_table_attr()
helper. This prevents the ROM image from being saved correctly during a
mixed mode boot.

Fixes: 2c3625cb ("efi/x86: Fold __setup_efi_pci32() and __setup_efi_pci64() into one function")
Signed-off-by: Mikel Rychliski <mikel@mikelr.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

drivers/firmware/efi/libstub/x86-stub.c

@@ -72,7 +72,7 @@ preserve_pci_rom_image(efi_pci_io_protocol_t *pci, struct pci_setup_rom **__rom)
 	rom->data.type	= SETUP_PCI;
 	rom->data.len	= size - sizeof(struct setup_data);
 	rom->data.next	= 0;
-	rom->pcilen	= pci->romsize;
+	rom->pcilen	= romsize;
 	*__rom = rom;
 
 	status = efi_call_proto(pci, pci.read, EfiPciIoWidthUint16,