[ARM] sun4i: Make device tree and bindings linux-like

This patch mainly focuses on making sun4i device tree much more
closer to linux sun4i device tree. To achieve this we do the
following changes in this patch:
1. Rename common/sunxi/timer.c to common/sunxi/sun4i_timer.c
2. Update device tree compatible string of sun4i_timer
3. Rename common/sunxi/intc.c to common/sunxi/irq-sun4i.c
4. Update device tree compatible string of irq-sun4i.c
5. Update device tree compatible string of drivers/mmc/host/sunxi_mmc.c
6. Rename sun4i/dts/sun4i.dtsi to sun4i/dts/sun4i-a10.dtsi
7. Add clocking related information to sun4i/dts/sun4i-a10.dtsi
8. Call of_clk_init() from arch_board_early_init()

Signed-off-by: Anup Patel <anup@brainfault.org>