util/nvmutil: initialise w in gbe_cat_buf

no build error at the moment, nor would there be if
using clang or gcc, but i imagine some buggy compilers
might complain.

remember: portability. i also want this code to compile
on old, buggy compilers.

logically, this initialisation is redundant.

Signed-off-by: Leah Rowe <leah@libreboot.org>

util/nvmutil/nvmutil.c

@@ -1133,7 +1133,7 @@ static void
 gbe_cat_buf(uint8_t *b)
 {
 	size_t wc;
-	ssize_t w;
+	ssize_t w = 0;
 
 	for (wc = 0; wc < GBE_PART_SIZE; wc += w)
 		if ((w = write(STDOUT_FILENO, b + wc, GBE_PART_SIZE - wc)) < 1)