cxgb3: fix out of bounds read

An out of bounds read of 2 bytes was discovered in cxgb3 with KASAN.

t3_config_rss() expects both arrays it gets as parameters to have
terminators. setup_rss(), the caller, forgets to add a terminator to
one of the arrays. Thankfully the iteration in t3_config_rss() stops
anyway, but in the last iteration the check for the terminator
is an out of bounds read.

Add the missing terminator to rspq_map[].

Reported-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: Michal Schmidt <mschmidt@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>