bcache: Bkey indexing renaming

More refactoring:

node() -> bset_bkey_idx()
end() -> bset_bkey_last()

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

diff --cc drivers/md/bcache/bcache.h
Simple merge

diff --cc drivers/md/bcache/bset.c
Simple merge

diff --cc drivers/md/bcache/bset.h
Simple merge

diff --cc drivers/md/bcache/btree.c
Simple merge

diff --cc drivers/md/bcache/debug.c
Simple merge

diff --cc drivers/md/bcache/journal.c
Simple merge

diff --cc include/uapi/linux/bcache.h
Simple merge