crypto: nx - fix spelling mistake: "availavle" -> "available"

Trivial fix to spelling mistake in pr_err error message text. Also
fix spelling mistake in proceeding comment.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Haren Myneni <haren@us.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>