dt-bindings: PCI: hisi: Delete the obsolete HiSilicon PCIe file

The hisilicon-pcie.txt file is no longer useful since commit
c2fa6cf (PCI: dwc: hisi: Remove non-ECAM HiSilicon
hip05/hip06 driver), so delete it and remove related code in
MAINTAINERS file.

Suggested-by: Zhou Wang <wangzhou1@hisilicon.com>
Link: https://lore.kernel.org/r/1617111799-109749-1-git-send-email-liudongdong3@huawei.com
Signed-off-by: Dongdong Liu <liudongdong3@huawei.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Krzysztof Wilczyński <kw@linux.com>

Author: liudongdong3

Documentation/devicetree/bindings/pci/hisilicon-pcie.txt

@@ -13899,7 +13899,6 @@ PCIE DRIVER FOR HISILICON
 M:	Zhou Wang <wangzhou1@hisilicon.com>
 L:	linux-pci@vger.kernel.org
 S:	Maintained
-F:	Documentation/devicetree/bindings/pci/hisilicon-pcie.txt
 F:	drivers/pci/controller/dwc/pcie-hisi.c
 
 PCIE DRIVER FOR HISILICON KIRIN