Tegra20: Move some include files to arch-tegra for sharing with Tegra30

The move is pretty straight-forward. ap20.h and tegra20.h were renamed to ap.h and tegra.h.
Some files remain in arch-tegra20 but 'include' a file in 'arch-tegra' with #defines & structs
that will be common between T20 and T30 HW. HW-specific #defines, etc. stay in the 'arch-tegra20'
'root' file.

All boards build OK w/MAKEALL -s tegra20. Checkpatch.pl runs clean. Seaboard works OK.

Signed-off-by: Tom Warren <twarren@nvidia.com>
diff --git a/arch/arm/cpu/tegra20-common/pmu.c b/arch/arm/cpu/tegra20-common/pmu.c
index 53505e9..2282953 100644
--- a/arch/arm/cpu/tegra20-common/pmu.c
+++ b/arch/arm/cpu/tegra20-common/pmu.c
@@ -24,10 +24,10 @@
 #include <common.h>
 #include <tps6586x.h>
 #include <asm/io.h>
-#include <asm/arch/ap20.h>
-#include <asm/arch/tegra20.h>
-#include <asm/arch/tegra_i2c.h>
-#include <asm/arch/sys_proto.h>
+#include <asm/arch/tegra.h>
+#include <asm/arch-tegra/ap.h>
+#include <asm/arch-tegra/tegra_i2c.h>
+#include <asm/arch-tegra/sys_proto.h>
 
 #define VDD_CORE_NOMINAL_T25	0x17	/* 1.3v */
 #define VDD_CPU_NOMINAL_T25	0x10	/* 1.125v */