CRC7 support

Add CRC7 routines, used for example in MMC over SPI communication.
Kerneldoc updates

[akpm@linux-foundation.org: fix funny mix of const and non-const]
Signed-off-by: Jan Nikitenko <jan.nikitenko@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/Kconfig

diff --git a/lib/Kconfig b/lib/Kconfig
index 3eb29d5..e5c2c51 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -41,6 +41,14 @@
 	  kernel tree does. Such modules that use library CRC32 functions
 	  require M here.
 
+config CRC7
+	tristate "CRC7 functions"
+	help
+	  This option is provided for the case where no in-kernel-tree
+	  modules require CRC7 functions, but a module built outside
+	  the kernel tree does. Such modules that use library CRC7
+	  functions require M here.
+
 config LIBCRC32C
 	tristate "CRC32c (Castagnoli, et al) Cyclic Redundancy-Check"
 	help