bnx2x: Revert UNDI flushing mechanism

Commit 91ebb929 ("bnx2x: Add support for Multi-Function UNDI") [which was
later supposedly fixed by de682941 ("bnx2x: Fix UNDI driver unload")]
introduced a bug in which in some [yet-to-be-determined] scenarios the
alternative flushing mechanism which was to guarantee the Rx buffers are
empty before resetting them during device probe will fail.
If this happens, when device will be loaded once more a fatal attention will
occur; Since this most likely happens in boot from SAN scenarios, the machine
will fail to load.

Notice this may occur not only in the 'Multi-Function' scenario but in the
regular scenario as well, i.e., this introduced a regression in the driver's
ability to perform boot from SAN.

The patch reverts the mechanism and applies the old scheme to multi-function
devices as well as to single-function devices.

Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>