s390: zcrypt: initialize variables before_use

s390: zcrypt: initialize variables before_use

The 'func_code' variable gets printed in debug statements without
a prior initialization in multiple functions, as reported when building
with clang:

drivers/s390/crypto/zcrypt_api.c:659:6: warning: variable 'func_code' is used uninitialized whenever 'if' condition is true
      [-Wsometimes-uninitialized]
        if (mex->outputdatalength < mex->inputdatalength) {
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/s390/crypto/zcrypt_api.c:725:29: note: uninitialized use occurs here
        trace_s390_zcrypt_rep(mex, func_code, rc,
                                   ^~~~~~~~~
drivers/s390/crypto/zcrypt_api.c:659:2: note: remove the 'if' if its condition is always false
        if (mex->outputdatalength < mex->inputdatalength) {
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/s390/crypto/zcrypt_api.c:654:24: note: initialize the variable 'func_code' to silence this warning
        unsigned int func_code;
                              ^

Add initializations to all affected code paths to shut up the warning
and make the warning output consistent.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>