ARM: 8996/1: Documentation/Clean up the description of mach-<class>

Polish the description of machine classes a little bit,
remove the duplicate directory name, so the reader does
not feel compelled to dig through the output of "git blame".
Signed-off-by: Pete Zaitcev <zaitcev@yahoo.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

Documentation/arm/arm.rst

@@ -184,10 +184,8 @@ Kernel entry (head.S)
   We group machine (or platform) support code into machine classes.  A
   class typically based around one or more system on a chip devices, and
   acts as a natural container around the actual implementations.  These
-  classes are given directories - arch/arm/mach-<class> and
-  arch/arm/mach-<class> - which contain the source files to/include/mach
-  support the machine class.  This directories also contain any machine
-  specific supporting code.
+  classes are given directories - arch/arm/mach-<class> - which contain
+  the source files and include/mach/ to support the machine class.
 
   For example, the SA1100 class is based upon the SA1100 and SA1110 SoC
   devices, and contains the code to support the way the on-board and off-