PCI: j721e: Use devm_clk_get_optional_enabled() to get and enable the clock

PCI: j721e: Use devm_clk_get_optional_enabled() to get and enable the clock

Use devm_clk_get_optional_enabled() helper instead of calling
devm_clk_get_optional() and then clk_prepare_enable().

Assign the result of devm_clk_get_optional_enabled() directly to
pcie->refclk to avoid using a local 'clk' variable.

Signed-off-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Link: https://patch.msgid.link/20251028154229.6774-2-linux.amoon@gmail.com