PCI: kirin: Use devm_kasprintf() to dynamically allocate clock names

Use devm_kasprintf() instead of open coding it.  This saves the need of
an intermediate buffer.

There was also no reason to use devm_kstrdup_const() as string is known
to be constant.

[kwilczynski: commit log, and add missing Reviewed-by tag]
Link: https://lore.kernel.org/linux-pci/1bad6879083a7d836c8a47418a0afa22485e8f69.1700294127.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>