mpc8641: Fix error in README

I made some updates to the code that didn't make it into the
README - fix this

Signed-off-by: Becky Bruce <becky.bruce@freescale.com>

doc/README.mpc8641hpcn

@@ -134,15 +134,15 @@ For 36-bit-enabled u-boot, the virtual map is the same as for 32-bit.
 However, the physical map is altered to reside in 36-bit space, as follows.
 Addresses are no longer mapped with VA == PA.  All accesses from
 software use the VA; the PA is only used for setting up windows
-and mappings. Note that the low 32 bits are the same as the VA above;
-only the top 4 bits vary:
+and mappings. Note that with the exception of PCI MEM and RIO, the low
+ 32 bits are the same as the VA above; only the top 4 bits vary:
 
 	Memory Range			Device		Size
 	------------			------		----
 	0x0_0000_0000	0x0_7fff_ffff	DDR		2G
-	0xc_8000_0000	0xc_9fff_ffff	RIO MEM		512M
-	0xc_8000_0000	0xc_9fff_ffff	PCI1/PEX1 MEM	512M
-	0xc_a000_0000	0xc_bfff_ffff	PCI2/PEX2 MEM	512M
+	0xc_0000_0000	0xc_1fff_ffff	RIO MEM		512M
+	0xc_0000_0000	0xc_1fff_ffff	PCI1/PEX1 MEM	512M
+	0xc_2000_0000	0xc_3fff_ffff	PCI2/PEX2 MEM	512M
 	0xf_ffe0_0000	0xf_ffef_ffff	CCSR		1M
 	0xf_ffdf_0000	0xf_ffdf_7fff	PIXIS		8K
 	0xf_ffdf_8000	0xf_ffdf_ffff	CF		8K