yaffs: Remove SHORT_NAMES_IN_RAM and WIDE_TNODE_DISABLE configs

These have been removed from Linux as their use is discouraged except
for debugging purposes.

The logic has also changed for SHORT_NAMES_IN_RAM. This is now negative
logic. Set  CONFIG_YAFFS_NO_SHORT_NAMES to **disable** short names.

Signed-off-by: Charles Manning <cdhmanning@gmail.com>