can: m_can: Add check for devm_clk_get

Since the devm_clk_get may return error,
it should be better to add check for the cdev->hclk,
as same as cdev->cclk.

Fixes: f524f829

 ("can: m_can: Create a m_can platform framework")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Link: https://lore.kernel.org/all/20221123063651.26199-1-jiasheng@iscas.ac.cn
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>