tests-crypto/test-crypto.h: update api to const input buffers
tests-crypto/test-crypto.h: update api to const input buffers

Input buffers are not modified, so can be declared const arguments.
This will allow using `const` inputs for `modes/ccm` tests.

kYc0o/RIOT,x3ro/RIOT,lazytech-org/RIOT,OTAkeys/RIOT,kaspar030/RIOT,jasonatran/RIOT,OTAkeys/RIOT,josephnoir/RIOT,yogo1212/RIOT,smlng/RIOT,rfuentess/RIOT,ant9000/RIOT,mtausig/RIOT,authmillenon/RIOT,cladmi/RIOT,kYc0o/RIOT,OTAkeys/RIOT,kaspar030/RIOT,x3ro/RIOT,jasonatran/RIOT,authmillenon/RIOT,x3ro/RIOT,yogo1212/RIOT,A-Paul/RIOT,mtausig/RIOT,cladmi/RIOT,lazytech-org/RIOT,ant9000/RIOT,biboc/RIOT,miri64/RIOT,biboc/RIOT,kYc0o/RIOT,RIOT-OS/RIOT,rfuentess/RIOT,biboc/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,aeneby/RIOT,mfrey/RIOT,toonst/RIOT,rfuentess/RIOT,OlegHahm/RIOT,A-Paul/RIOT,basilfx/RIOT,kaspar030/RIOT,OTAkeys/RIOT,cladmi/RIOT,aeneby/RIOT,kaspar030/RIOT,yogo1212/RIOT,miri64/RIOT,RIOT-OS/RIOT,basilfx/RIOT,BytesGalore/RIOT,jasonatran/RIOT,josephnoir/RIOT,yogo1212/RIOT,ant9000/RIOT,mtausig/RIOT,OlegHahm/RIOT,biboc/RIOT,OlegHahm/RIOT,A-Paul/RIOT,BytesGalore/RIOT,rfuentess/RIOT,lazytech-org/RIOT,cladmi/RIOT,yogo1212/RIOT,toonst/RIOT,cladmi/RIOT,toonst/RIOT,gebart/RIOT,gebart/RIOT,rfuentess/RIOT,smlng/RIOT,jasonatran/RIOT,mfrey/RIOT,mfrey/RIOT,basilfx/RIOT,RIOT-OS/RIOT,lazytech-org/RIOT,mfrey/RIOT,miri64/RIOT,mtausig/RIOT,jasonatran/RIOT,gebart/RIOT,smlng/RIOT,kYc0o/RIOT,basilfx/RIOT,basilfx/RIOT,mfrey/RIOT,aeneby/RIOT,kYc0o/RIOT,OTAkeys/RIOT,mtausig/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,toonst/RIOT,x3ro/RIOT,ant9000/RIOT,A-Paul/RIOT,A-Paul/RIOT,gebart/RIOT,BytesGalore/RIOT,josephnoir/RIOT,toonst/RIOT,BytesGalore/RIOT,gebart/RIOT,miri64/RIOT,OlegHahm/RIOT,x3ro/RIOT,josephnoir/RIOT,josephnoir/RIOT,lazytech-org/RIOT,smlng/RIOT,smlng/RIOT,biboc/RIOT,miri64/RIOT,aeneby/RIOT,yogo1212/RIOT,aeneby/RIOT,authmillenon/RIOT,OlegHahm/RIOT,authmillenon/RIOT,ant9000/RIOT,authmillenon/RIOT,BytesGalore/RIOT