util/ifdtool: Add find_fd null check

As the previous comment indicated, this null check is
currently superfluous, but adding it in makes Coverity
happy, and future-proofs the code in case someone changes
the internals of 'find_fcba' later and forgets/doesn't know
to update this error check.

Found-by: Coverity Scan #1395066
Signed-off-by: Jacob Garber <jgarber1@ualberta.ca>
Change-Id: I594cd0098f5b36cef5b3efc4c904710d3ba9b815
Reviewed-on: https://review.coreboot.org/c/coreboot/+/32691
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

util/ifdtool/ifdtool.c

@@ -236,7 +236,7 @@ static int get_ifd_version_from_fcba(char *image, int size)
 	int read_freq;
 	const fcba_t *fcba = find_fcba(image, size);
 	const fdbar_t *fdb = find_fd(image, size);
-	if (!fcba) /* a valid fcba indicates a valid fdb */
+	if (!fcba || !fdb)
 		exit(EXIT_FAILURE);
 
 	chipset = guess_ich_chipset(fdb);