The J721E PCIe is hardware specific to TI SoC parts so add a dependency
on that so it's available for those SoC parts and for compile testing but
not necessarily everyone who enables the Cadence PCIe controller.

Link: https://lore.kernel.org/linux-pci/20240104213910.1426843-1-pbrobinson@gmail.comSigned-off-by: Peter Robinson <pbrobinson@gmail.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>