module: rename __kstrtab_ns_* to __kstrtabns_* to avoid symbol conflict
The module namespace produces __strtab_ns_<sym> symbols to store
namespace strings, but it does not guarantee the name uniqueness.
This is a potential problem because we have exported symbols starting
with "ns_".
For example, kernel/capability.c exports the following symbols:
The former expands to "__kstrtab_ns_capable" and "__kstrtab_ns_ns_capable",
and the latter to "__kstrtab_capable" and "__kstrtab_ns_capable".
Then, we have the duplicated "__kstrtab_ns_capable".
To ensure the uniqueness, rename "__kstrtab_ns_*" to "__kstrtabns_*".