staging: ccree: Fix unnecessary NULL check before kfree'ing it

kfree(NULL) is safe and their is no need for a NULL check. Pointed out
by checkpatch.

Signed-off-by: Suniel Mahesh <sunil.m@techveda.org>
Acked-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>