PCI: controller: Add missing MODULE_DESCRIPTION() macros

When ARCH=x86, make allmodconfig && make W=1 C=1 reports:

  WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/pci/controller/dwc/pci-exynos.o
  WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/pci/controller/pci-host-generic.o
  WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/pci/controller/pcie-altera.o
  WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/pci/controller/pcie-altera-msi.o
  WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/pci/controller/pcie-mediatek.o
  WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/pci/controller/pcie-mediatek-gen3.o
  WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/pci/controller/vmd.o
  WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/pci/controller/pcie-apple.o
  WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/pci/controller/pcie-mt7621.o

Add the missing MODULE_DESCRIPTION() macro.

[kwilczynski: update MODULE_DESCRIPTION() text, commit log]
Link: https://lore.kernel.org/linux-pci/20240626-md-drivers-pci-controller-v2-1-94c811db7a51@quicinc.com


Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Krzysztof Wilczyński <kwilczynski@kernel.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Acked-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Acked-by: Sergio Paracuellos <sergio.paracuellos@gmail.com> # MT7621