Remove unnecessary cleanup assignment in SHA1Final()
This makes some static analyzers complain about stored value never being
read. While it is good to clear some other temporary variables, this
local variable i has no security private information (it has a fixed
value of 20 here) and trying to clear it to 0 does not add any value.
Remove that part of the "wipe variables" to avoid one useless static
analyzer complaint.
Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>