PCI: dwc: Clean up Kconfig dependencies (PCIE_DW_EP)

The "depends on" Kconfig construct is a no-op in options that
are selected and therefore has no effect. Remove it.

Clean up the users of PCIE_DW_EP and introduce idiom

	depends on PCI_ENDPOINT
	select PCIE_DW_EP

for all of them.

Link: https://lore.kernel.org/r/20210623140103.47818-2-andriy.shevchenko@linux.intel.com


Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>