fs/befs/btree.c: remove unneeded initializations

bh, od_sup and this_node are unconditionally initialized in
befs_bt_read_super() and befs_btree_find()

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>