qed: Delete redundant doorbell recovery types

DB_REC_DRY_RUN (running doorbell recovery without sending doorbells) is
never used. DB_REC_ONCE (send a single doorbell from the doorbell recovery)
is not needed anymore because by running the periodic handler we make sure
we check the overflow status later instead.
This patch is needed because in the next patches, the only doorbell
recovery type being used is DB_REC_REAL_DEAL, and the fixes are much
cleaner without this enum.

Signed-off-by: Denis Bolotin <dbolotin@marvell.com>
Signed-off-by: Michal Kalderon <mkalderon@marvell.com>
Signed-off-by: Ariel Elior <aelior@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>