Revert "skge: fix ram buffer size calculation"

This reverts commit 7fb7ac241162dc51ec0f7644d4a97b2855213c32.

Heikki Orsila reports that it causes a regression:

"Doing

nc host port < /dev/zero

on a sending machine (not skge) to an skge machine that is receiving:

nc -l -p port >/dev/null

with ~60 MiB/s speed, causes the interface go malfunct. A slow
transfer doesn't cause a problem."

See

http://bugzilla.kernel.org/show_bug.cgi?id=9321

for some more information.

There is a workaround (also reported by Heikki):

"After some fiddling, I noticed that not changing the register write
order on patch:

+ skge_write32(hw, RB_ADDR(q, RB_END), end);
skge_write32(hw, RB_ADDR(q, RB_WP), start);
skge_write32(hw, RB_ADDR(q, RB_RP), start);
- skge_write32(hw, RB_ADDR(q, RB_END), end);

fixes the visible effect.. Possibly not the root cause of the
problem, but changing the order back fixes networking here."

but that has yet to be ack'ed or tested more widely, so the whole
problem-causing commit gets reverted until this is resolved properly.

Bisected-and-requested-by: Heikki Orsila <shdl@zakalwe.fi>
Cc: Stephen Hemminger <shemminger@linux-foundation.org>
Cc: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>