ext2: guard reservation window dump with EXT2FS_DEBUG

ext2: guard reservation window dump with EXT2FS_DEBUG

The function __rsv_window_dump() is a heavyweight debug tool that walks
the reservation red-black tree. It is currently guarded by #if 1,
forcing it to be compiled into all kernels, even production ones.

Match the rest of the file by guarding it with #ifdef EXT2FS_DEBUG,
so it is only included when explicit debugging is enabled.

This removes the unused function code from standard builds.

Signed-off-by: Milos Nikic <nikic.milos@gmail.com>
Link: https://patch.msgid.link/20260207022920.258247-1-nikic.milos@gmail.com
Signed-off-by: Jan Kara <jack@suse.cz>