remoteproc: return error for bad "recovery" debugfs input

If the value written to the "recovery" debugfs file is not one of
the recognized commands return an error to indicate it's invalid.

Signed-off-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/20200228183359.16229-5-elder@linaro.org
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
diff --git a/drivers/remoteproc/remoteproc_debugfs.c b/drivers/remoteproc/remoteproc_debugfs.c
index b87565a..d734cad 100644
--- a/drivers/remoteproc/remoteproc_debugfs.c
+++ b/drivers/remoteproc/remoteproc_debugfs.c
@@ -146,6 +146,8 @@ rproc_recovery_write(struct file *filp, const char __user *user_buf,
 	} else if (!strncmp(buf, "recover", count)) {
 		/* begin the recovery process without changing the flag */
 		rproc_trigger_recovery(rproc);
+	} else {
+		return -EINVAL;
 	}
 
 	return count;