soc/tegra: fuse: Add FUSE clock check in tegra_fuse_readl()

tegra_fuse_readl() can be called from drivers at any time. If this API
is called before tegra_fuse_probe(), we end up enabling the clock before
it is registered. Add a check for the FUSE clock in tegra_fuse_readl()
and propagate any errors.
Signed-off-by: Nagarjuna Kristam <nkristam@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/soc/tegra/fuse/fuse-tegra.c

@@ -186,9 +186,12 @@ u32 __init tegra_fuse_read_early(unsigned int offset)
 
 int tegra_fuse_readl(unsigned long offset, u32 *value)
 {
-	if (!fuse->read)
+	if (!fuse->read || !fuse->clk)
 		return -EPROBE_DEFER;
 
+	if (IS_ERR(fuse->clk))
+		return PTR_ERR(fuse->clk);
+
 	*value = fuse->read(fuse, offset);
 
 	return 0;