Squashfs: update Kconfig and documentation for LZO

Update compression types supported and add some help text for
the LZO Kconfig option.

Also add missing "default n" line and make some trivial whitespace
cleanups too.
Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>

Documentation/filesystems/squashfs.txt

@@ -2,7 +2,7 @@ SQUASHFS 4.0 FILESYSTEM
 =======================
 
 Squashfs is a compressed read-only filesystem for Linux.
-It uses zlib compression to compress files, inodes and directories.
+It uses zlib/lzo compression to compress files, inodes and directories.
 Inodes in the system are very small and all blocks are packed to minimise
 data overhead. Block sizes greater than 4K are supported up to a maximum
 of 1Mbytes (default block size 128K).

fs/squashfs/Kconfig

@@ -5,13 +5,13 @@ config SQUASHFS
 	help
 	  Saying Y here includes support for SquashFS 4.0 (a Compressed
 	  Read-Only File System).  Squashfs is a highly compressed read-only
-	  filesystem for Linux.  It uses zlib compression to compress both
+	  filesystem for Linux.  It uses zlib/lzo compression to compress both
 	  files, inodes and directories.  Inodes in the system are very small
 	  and all blocks are packed to minimise data overhead. Block sizes
 	  greater than 4K are supported up to a maximum of 1 Mbytes (default
 	  block size 128K).  SquashFS 4.0 supports 64 bit filesystems and files
 	  (larger than 4GB), full uid/gid information, hard links and
-	  timestamps.  
+	  timestamps.
 
 	  Squashfs is intended for general read-only filesystem use, for
 	  archival use (i.e. in cases where a .tar.gz file may be used), and in
@@ -40,11 +40,21 @@ config SQUASHFS_XATTR
 config SQUASHFS_LZO
 	bool "Include support for LZO compressed file systems"
 	depends on SQUASHFS
+	default n
 	select LZO_DECOMPRESS
+	help
+	  Saying Y here includes support for reading Squashfs file systems
+	  compressed with LZO compresssion.  LZO compression is mainly
+	  aimed at embedded systems with slower CPUs where the overheads
+	  of zlib are too high.
 
-config SQUASHFS_EMBEDDED
+	  LZO is not the standard compression used in Squashfs and so most
+	  file systems will be readable without selecting this option.
 
-	bool "Additional option for memory-constrained systems" 
+	  If unsure, say N.
+
+config SQUASHFS_EMBEDDED
+	bool "Additional option for memory-constrained systems"
 	depends on SQUASHFS
 	default n
 	help