bnx2x: reorganization and beautification

Slightly changes the bnx2x code without `true' functional changes.
Changes include:
 1. Gathering macros into a single macro when combination is used multiple
    times.
 2. Exporting parts of functions into their own functions.
 3. Return values after if-else instead of only on the else condition
    (where current flow would simply return same value later in the code)
 4. Removing some unnecessary code (either dead-code or incorrect conditions)

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