Fix NULL pointer reference in board_flash_enable

Was introduced in r926. Found by Henrik Kretzschmar <henne@nachtwindheim.de>.

Corresponding to flashrom svn r930.
Signed-off-by: Michael Karcher <flashrom@mkarcher.dialup.fu-berlin.de>
Acked-by: Maciej Pijanka <maciej.pijanka@gmail.com>

board_enable.c

@@ -1445,7 +1445,7 @@ int board_flash_enable(const char *vendor, const char *part)
 	if (!board)
 		board = board_match_pci_card_ids();
 
-        if (board->status == NT) {
+        if (board && board->status == NT) {
                 if (!force_boardenable)
                 {
                         printf("WARNING: Your mainboard is %s %s, but the mainboard-specific\n"