Staging: most: mostcore/core.c. Fix "Using plain integer as NULL pointer" warnings

This patch fixes the warning generated by sparse: "Using plain integer
as NULL pointer" by replacing the pointer test against 0 with a logical test.

Signed-off-by: Adrian Remonda <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/most/mostcore/core.c

···
 	if (ret)
 		return ret;
 
-	if (mdev_devnod == 0 || *mdev_devnod == 0) {
+	if (!mdev_devnod || *mdev_devnod == 0) {
 		snprintf(devnod_buf, sizeof(devnod_buf), "%s-%s", mdev, mdev_ch);
 		mdev_devnod = devnod_buf;
 	}