qed: Fix BAR size split for some servers

Can't rely on pci config space to discover bar size,
as in some environments this returns a wrong, too large value.
Instead, rely on device register, which contains the value
provided by MFW at preboot.

Signed-off-by: Ariel Elior <Ariel.Elior@qlogic.com>
Signed-off-by: Manish Chopra <manish.chopra@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>