Set pci devices MPS/MRRS to max supported value.

This seems to workaround issues where using TPU and streaming
camera frames was causing MIPI CSI fifo overflows.

Change-Id: I296ff24b0b17ee63fb93f778bf10351f739f8142
diff --git a/debian/boot.txt b/debian/boot.txt
index 80d0a7a..76f9873 100644
--- a/debian/boot.txt
+++ b/debian/boot.txt
@@ -12,7 +12,7 @@
     setenv root ${mmc_root}
 fi
 
-cmdline="console=ttymxc0,115200 console=tty0 earlycon=ec_imx6q,0x30860000,115200 root=${root} rootfstype=ext4 rw rootwait init=/sbin/init net.ifnames=0"
+cmdline="console=ttymxc0,115200 console=tty0 earlycon=ec_imx6q,0x30860000,115200 root=${root} rootfstype=ext4 rw rootwait init=/sbin/init net.ifnames=0 pci=pcie_bus_perf"
 
 ext2load mmc ${bootdev}:1 ${loadaddr} ${image}
 ext2load mmc ${bootdev}:1 ${fdt_addr} ${fdt_file}