kfifo: add example files to the kernel sample directory

Add four examples to the kernel sample directory.

It shows how to handle:
- a byte stream fifo
- a integer type fifo
- a dynamic record sized fifo
- the fifo DMA functions

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Stefani Seibold <stefani@seibold.net>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

samples/Kconfig

@@ -44,4 +44,14 @@ config SAMPLE_HW_BREAKPOINT
 	help
 	  This builds kernel hardware breakpoint example modules.
 
+config SAMPLE_KFIFO
+	tristate "Build kfifo examples -- loadable modules only"
+	depends on m
+	help
+	  This config option will allow you to build a number of
+	  different kfifo sample modules showing how to use the
+	  generic kfifo API.
+
+	  If in doubt, say "N" here.
+
 endif # SAMPLES