ARM: tegra: move Tegra specific code under arch/arm/

This patch moves Tegra specific directory entries
from the toplevel Makefile and spl/Makefile
to arch/arm/cpu/*/Makefile using Kbuild descending feature.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Tom Warren <TWarren@nvidia.com>
diff --git a/arch/arm/cpu/arm720t/Makefile b/arch/arm/cpu/arm720t/Makefile
index 243a123..6badb3b 100644
--- a/arch/arm/cpu/arm720t/Makefile
+++ b/arch/arm/cpu/arm720t/Makefile
@@ -7,3 +7,5 @@
 
 extra-y	= start.o
 obj-y	= interrupts.o cpu.o
+
+obj-$(CONFIG_TEGRA) += tegra-common/