Revert "KEYS: encrypted: Add check for strsep"

This reverts commit b4af096b.

New encrypted keys are created either from kernel-generated random
numbers or user-provided decrypted data.  Revert the change requiring
user-provided decrypted data.

Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>