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/drivers/spi/tegra_spi.c b/drivers/spi/tegra_spi.c
index 18b00b2..9bb34e2 100644
--- a/drivers/spi/tegra_spi.c
+++ b/drivers/spi/tegra_spi.c
@@ -23,16 +23,15 @@
  */
 
 #include <common.h>
-
 #include <malloc.h>
-#include <spi.h>
 #include <asm/io.h>
 #include <asm/gpio.h>
-#include <asm/arch/clk_rst.h>
 #include <asm/arch/clock.h>
 #include <asm/arch/pinmux.h>
 #include <asm/arch/uart-spi-switch.h>
-#include <asm/arch/tegra_spi.h>
+#include <asm/arch-tegra/clk_rst.h>
+#include <asm/arch-tegra/tegra_spi.h>
+#include <spi.h>
 
 #if defined(CONFIG_SPI_CORRUPTS_UART)
  #define corrupt_delay()	udelay(CONFIG_SPI_CORRUPTS_UART_DLY);