logging: sys_t/catalog: fix unaligned access

When copying parameters into payload buffer, it is possible
that after copying a string over, the pointer to buffer is
no longer aligned on 4 or 8 bytes. And some toolchains may
decide to treat the copy as aligned since the values being
copied are 4 or 8 bytes. This results in unaligned memory
access and hardware exception. So change the copy to memcpy
to avoid potential unaligned access.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>