Documentation: fix minor typos/spelling

Fix some minor typos:
 * informations => information
 * there own => their own
 * these => this

Signed-off-by: Sylvestre Ledru <sylvestre.ledru@scilab.org>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/powerpc/platforms/Kconfig b/arch/powerpc/platforms/Kconfig
index 2057682..f7b0772 100644
--- a/arch/powerpc/platforms/Kconfig
+++ b/arch/powerpc/platforms/Kconfig
@@ -46,7 +46,7 @@
 	help
 	  Support from booting from Open Firmware or yaboot using an
 	  Open Firmware client interface. This enables the kernel to
-	  communicate with open firmware to retrieve system informations
+	  communicate with open firmware to retrieve system information
 	  such as the device tree.
 
 	  In case of doubt, say Y