drm/tinydrm: mipi-dbi: Silence: ‘cmd’ may be used uninitialized

Fix this warning:
drivers/gpu/drm/tinydrm/mipi-dbi.c: In function ‘mipi_dbi_debugfs_command_write’:
drivers/gpu/drm/tinydrm/mipi-dbi.c:905:8: warning: ‘cmd’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  ret = mipi_dbi_command_buf(mipi, cmd, parameters, i);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

cmd can't be used uninitialized, but to satisfy the compiler,
initialize it to zero.
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/tinydrm/mipi-dbi.c

@@ -863,7 +863,7 @@ static ssize_t mipi_dbi_debugfs_command_write(struct file *file,
 {
 	struct seq_file *m = file->private_data;
 	struct mipi_dbi *mipi = m->private;
-	u8 val, cmd, parameters[64];
+	u8 val, cmd = 0, parameters[64];
 	char *buf, *pos, *token;
 	unsigned int i;
 	int ret;