staging: ccree: simplify freeing SRAM memory address

The code freeing the SRAM memory address was zeroing the address
on release although there is nothing secret about it. Simplify
the code by simply calling kfree directly.

Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>