sunxi: use CONFIG_SYS_CLK_FREQ to set cpu clock

make the CPU clock selectable via Kconfig

this removes the sunxi specific CONFIG_CLK_FULL_SPEED defined in each
soc header and replaces it's use in board/sunxi/board.c with
CONFIG_SYS_CLK_FREQ from Kconfig which allows us to configure board
specific frequency on boot

Signed-off-by: Iain Paton <ipaton0@gmail.com>
[hdegoede@redhat.com s/CONFIG_SYS_CLK_FREQ/CONFIG_TIMER_CLK_FREQ/ for the
 arch-timer clk speed on sun7i to fix mis-compile on sun7i]
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
index 9d0eb91..2fcab60 100644
--- a/board/sunxi/Kconfig
+++ b/board/sunxi/Kconfig
@@ -132,6 +132,10 @@
 
 endif
 
+config SYS_CLK_FREQ
+	default 912000000 if MACH_SUN7I
+	default 1008000000 if MACH_SUN4I || MACH_SUN5I || MACH_SUN6I || MACH_SUN8I
+
 config SYS_CONFIG_NAME
 	default "sun4i" if MACH_SUN4I
 	default "sun5i" if MACH_SUN5I