tools: gpio-hammer: fix spelling mistake: "occurences" -> "occurrences"

There is a spelling mistake in an error message. Fix it.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

tools/gpio/gpio-hammer.c

@@ -153,7 +153,7 @@ int main(int argc, char **argv)
 
 	if (i >= GPIOHANDLES_MAX) {
 		fprintf(stderr,
-			"Only %d occurences of '-o' are allowed, %d were found\n",
+			"Only %d occurrences of '-o' are allowed, %d were found\n",
 			GPIOHANDLES_MAX, i + 1);
 		return -1;
 	}