ASoC: jz4740-i2s: add missed checks for clk_get()

jz4740_i2s_set_sysclk() does not check the return values of clk_get(),
while the file dereferences the pointers in clk_put().
Add the missed checks to fix it.

Fixes: 11bd3dd1 ("ASoC: Add JZ4740 ASoC support")
Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Link: https://lore.kernel.org/r/20201203144227.418194-1-hslester96@gmail.com


Signed-off-by: Mark Brown <broonie@kernel.org>