ARM/PCI: Call pcie_bus_configure_settings() to set MPS

Call pcie_bus_configure_settings() on ARM, like for other platforms.
pcie_bus_configure_settings() makes sure the MPS across the bus is uniform
and provides the ability to tune the MRSS and MPS to higher performance
values.  This is particularly important for embedded where there is no
firmware to program these PCIe settings for the OS.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Russell King <linux@arm.linux.org.uk>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
CC: Santosh Shilimkar <santosh.shilimkar@ti.com>