MIPS: Lantiq: Make use of new PCI clock helper

MIPS: Lantiq: Make use of new PCI clock helper

Make use of the new helper function that allows us to set the PCI clock
delay inside the PCI driver.

Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/4115/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>