board/pc: fix typo in board/pc/post-build.sh

Signed-off-by: Grégoire Delattre <gregoire.delattre@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit 9f1256e1aae0a1e91e033d51b968415adec117bf)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

board/pc/post-build.sh

@@ -11,5 +11,5 @@ else
     cp -f "$BOARD_DIR/grub-bios.cfg" "$TARGET_DIR/boot/grub/grub.cfg"
 
     # Copy grub 1st stage to binaries, required for genimage
-    cp -f "$HOST_DIR/lib/grub/i387-pc/boot.img" "$BINARIES_DIR"
+    cp -f "$HOST_DIR/lib/grub/i386-pc/boot.img" "$BINARIES_DIR"
 fi