Revert "fs/nls: make load_nls() take a const parameter"

This reverts commit 952af5cf which is
commit c1ed39ec upstream.

It breaks the Android ABI and can be brought back later in an abi-safe
way if needed.

Bug: 161946584
Change-Id: I3ecb25cbffc28bc20e7e398ba4b36c71bf54a0bc
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>