Replace start-arm920t.S with start-arm.S

Replace start-arm920t.S with start-arm.S. This will allow for a common logic
to handle 

Signed-off-by: Nishanth Menon <x0nishan@ti.com>

--

arch/arm/cpu/Makefile

@@ -2,10 +2,8 @@ obj-y += cpu.o
 obj-y += interrupts.o
 
 #
-# start-arm920t.S and start-arm926ejs.S have been
-# merged to start-arm920t.S. More start-*.S should
-# be merged here and finally called start-arm.S
+# Any variants can be called as start-armxyz.S
 #
-obj-$(CONFIG_ARM920T) += start-arm920t.o
-obj-$(CONFIG_ARM926EJS) += start-arm920t.o
-obj-$(CONFIG_ARCH_IMX31) += start-arm920t.o
+obj-$(CONFIG_ARM920T) += start-arm.o
+obj-$(CONFIG_ARM926EJS) += start-arm.o
+obj-$(CONFIG_ARCH_IMX31) += start-arm.o