be2net: remove duplicate code in be_cmd_rx_filter()

This patch passes BE_IF_FLAGS_XXX flags to be_cmd_rx_filter() routine
instead of the IFF_XXX flags. Doing this gets rid of the code to convert
the IFF_XXX flags to the BE_IF_FLAGS_XXX used by the FW cmd. The patch
also removes code for setting if_flags_mask that was duplicated for each
filter mode.

Signed-off-by: Sathya Perla <sathya.perla@emulex.com>
Signed-off-by: Kalesh AP <kalesh.purayil@emulex.com>
Signed-off-by: David S. Miller <davem@davemloft.net>