Documentation: update kmemleak arch. info

Besides x86 and arm, kmemleak now supports powerpc, sparc, sh,
microblaze and tile.

Signed-off-by: Daniel Baluta <dbaluta@ixiacom.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/kmemleak.txt

@@ -11,6 +11,7 @@ with the difference that the orphan objects are not freed but only
 reported via /sys/kernel/debug/kmemleak. A similar method is used by the
 Valgrind tool (memcheck --leak-check) to detect the memory leaks in
 user-space applications.
+Kmemleak is supported on x86, arm, powerpc, sparc, sh, microblaze and tile.
 
 Usage
 -----
@@ -178,5 +179,4 @@ block doesn't need to be freed (some cases in the init_call functions),
 the pointer is calculated by other methods than the usual container_of
 macro or the pointer is stored in a location not scanned by kmemleak.
 
-Page allocations and ioremap are not tracked. Only the ARM and x86
-architectures are currently supported.
+Page allocations and ioremap are not tracked.