octeontx2-af: Fix uninitialized variable val

In the case where the condition !is_rvu_otx2(rvu) is false variable
val is not initialized and can contain a garbage value. Fix this by
initializing val to zero and bit-wise or'ing in BIT_ULL(51) to val
for the true condition case of !is_rvu_otx2(rvu).

Addresses-Coverity: ("Uninitialized scalar variable")
Fixes: 4b5a3ab1 ("octeontx2-af: Hardware configuration for inline IPsec")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>