[ARM] 3675/2: Preparing for AT91SAM926 support

Patch from Andrew Victor

This prepares the way for adding support for the new Atmel AT91SAM926x
processors.

Major changes:
- Rename time.c to at91rm9200_time.c
- Rename common.c to at91rm9200.c
- Introduce ARCH_AT91, of which ARCH_AT91RM9200, ARCH_AT91SAM9260 and
ARCH_AT91SAM9261 are dependent.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index a3bbaaf..3345c6d 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -114,7 +114,7 @@
  machine-$(CONFIG_ARCH_H720X)	   := h720x
  machine-$(CONFIG_ARCH_AAEC2000)   := aaec2000
  machine-$(CONFIG_ARCH_REALVIEW)   := realview
- machine-$(CONFIG_ARCH_AT91RM9200) := at91rm9200
+ machine-$(CONFIG_ARCH_AT91)       := at91rm9200
  machine-$(CONFIG_ARCH_EP93XX)     := ep93xx
  machine-$(CONFIG_ARCH_PNX4008)    := pnx4008
  machine-$(CONFIG_ARCH_NETX)       := netx