ptp: ocp: Fix uninitialized variable warning spotted by clang.

If attempting to flash the firmware with a blob of size 0,
the entire write loop is skipped and the uninitialized err
is returned.  Fix by setting to 0 first.

Fixes: 773bda9649 ("ptp: ocp: Expose various resources on the timecard.")
Signed-off-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/ptp/ptp_ocp.c

@@ -763,7 +763,7 @@ ptp_ocp_devlink_flash(struct devlink *devlink, struct device *dev,
 	size_t off, len, resid, wrote;
 	struct erase_info erase;
 	size_t base, blksz;
-	int err;
+	int err = 0;
 
 	off = 0;
 	base = bp->flash_start;