[asan] Fix kernel callback naming in instrumentation module.

Right now clang uses "_n" suffix for some user space callbacks and "N" for the matching kernel ones. There's no need for this and it actually breaks kernel build with inline instrumentation. Use the same callback names for user space and the kernel (and also make them consistent with the names GCC uses).

Patch by Andrey Konovalov.

Differential Revision: https://reviews.llvm.org/D42423

llvm-svn: 323470