bnx2: remove redundant initializations of pointers txr and rxr

Pointers txr and rxr are being initialized and a few statements later
are being assigned new values without the original values ever being
read. The initialized values are therefore redundant and can be
removed.

Cleans up clang warnings:
drivers/net/ethernet/broadcom/bnx2.c:5821:28: warning: Value stored to
'txr' during its initialization is never read
drivers/net/ethernet/broadcom/bnx2.c:5822:28: warning: Value stored to
'rxr' during its initialization is never read

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>