PCI: dwc: Remove not-going-to-be-supported code for Baikal SoC

PCI: dwc: Remove not-going-to-be-supported code for Baikal SoC

As noticed in the discussion [1] the Baikal SoC and platforms
are not going to be finalized, hence remove stale code.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/lkml/22b92ddf-6321-41b5-8073-f9c7064d3432@infradead.org/
Link: https://patch.msgid.link/20260220142600.2397070-1-andriy.shevchenko@linux.intel.com