Static checkers insist that the mpi_alloc() allocation can fail so add
a check to prevent a NULL dereference. Small allocations like this
can't actually fail in current kernels, but adding a check is very
simple and makes the static checkers happy.
Fixes: 6637e11e4ad2 ("crypto: rsa - allow only odd e and restrict value in FIPS mode") Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>