CRISv32: Fix potential null reference in cryptocop driver.

The code didn't test the pointer to the newly allocated
memory, but a parameter sent in as value.
Since the input parameter was most often set, the code
would have used a null pointer if the kmalloc failed.
If the input parameter was not set, the code would
leak the allocated buffer.

http://bugzilla.kernel.org/show_bug.cgi?id=11363

Reported-by: Daniel Marjamäki <danielm77@spray.se>
Signed-off-by: Jesper Nilsson <jesper.nilsson@axis.com>