myri10ge: use pcie_get/set_readrq

Based on a patch from Peter Oruba, convert myri10ge to use pcie_get_readrq()
and pcie_set_readrq() instead of our own PCI calls and arithmetics.

These driver changes incorporate the proposed PCI-X / PCI-Express read byte
count interface.  Reading and setting those values doesn't take place
"manually", instead wrapping functions are called to allow quirks for some
PCI bridges.

Signed-off-by: Brice Goglin <brice@myri.com>
Signed-off by: Peter Oruba <peter.oruba@amd.com>
Based on work by Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>