kasan: inline and rename kasan_unpoison_memory

Currently kasan_unpoison_memory() is used as both an external annotation
and as internal memory poisoning helper. Rename external annotation to
kasan_unpoison_data() and inline the internal helper for for hardware
tag-based mode to avoid undeeded function calls.

There's the external annotation kasan_unpoison_slab() that is currently
defined as static inline and uses kasan_unpoison_memory(). With this
change it's turned into a function call. Overall, this results in the
same number of calls for hardware tag-based mode as
kasan_unpoison_memory() is now inlined.

Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Link: https://linux-review.googlesource.com/id/Ia7c8b659f79209935cbaab3913bf7f082cc43a0e