sbsa-acs-drv: Removed unused PCIe PAL API's

- Changes made as part of deleting the SBSA tests not run
- Removed pal_pcie_scan_bridge_devices_and_check_memtype and
  pal_pcie_get_device_type implementations from sbsa-acs-drv.

Signed-off-by: Sujana M <sujana.m@arm.com>