drm/tegra: rgb: Fix missing clk_put() in the error handling paths of tegra_dc_rgb_probe()

If clk_get_sys(..., "pll_d2_out0") fails, the clk_get_sys() call must be
undone.

Add the missing clk_put and a new 'put_pll_d_out0' label in the error
handling path, and use it.

Fixes: 0c921b6d

 ("drm/tegra: dc: rgb: Allow changing PLLD rate on Tegra30+")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/0182895ead4e4730426616b0d9995954c960b634.1693667005.git.christophe.jaillet@wanadoo.fr