staging: keucr: Use strncmp() & strncpy() instead of custom functions

This patchset make some cleanup to staging/keucr. Use strncmp and strncpy instad of custom functions. Also some style cleanups.

The patches contained in this patchset are the following:

[PATCH 1/4] staging: keucr: Use strncmp() instead of custom StringCmp() and some style cleanups [PATCH 2/4] staging: keucr: Use strncpy() instead of custom StringCopy() and some style cleanups [PATCH 3/4] staging: keucr: Delete custom StringCmp() and StringCopy() functions [PATCH 4/4] staging: keucr: Delete use kernel strcmp() & strcpy() from TODO file