samples: uhid: fix warnings in uhid-example

Fix warnings seen when building for 32-bit architecture.

Use "%xd" for arguments of type size_t to fix the warnings.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>

samples/uhid/uhid-example.c

@@ -165,7 +165,7 @@ static int uhid_write(int fd, const struct uhid_event *ev)
 		fprintf(stderr, "Cannot write to uhid: %m\n");
 		return -errno;
 	} else if (ret != sizeof(*ev)) {
-		fprintf(stderr, "Wrong size written to uhid: %ld != %lu\n",
+		fprintf(stderr, "Wrong size written to uhid: %zd != %zu\n",
 			ret, sizeof(ev));
 		return -EFAULT;
 	} else {
@@ -236,7 +236,7 @@ static int event(int fd)
 		fprintf(stderr, "Cannot read uhid-cdev: %m\n");
 		return -errno;
 	} else if (ret != sizeof(ev)) {
-		fprintf(stderr, "Invalid size read from uhid-dev: %ld != %lu\n",
+		fprintf(stderr, "Invalid size read from uhid-dev: %zd != %zu\n",
 			ret, sizeof(ev));
 		return -EFAULT;
 	}