common: ep93xx: Move arch-specific declarations out of common

These declarations should not be in common. Remove those that are not
needed and move the others to an arch-specific location.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/cpu/arm920t/ep93xx/speed.c b/arch/arm/cpu/arm920t/ep93xx/speed.c
index 9dc60b6..f0ab7d4 100644
--- a/arch/arm/cpu/arm920t/ep93xx/speed.c
+++ b/arch/arm/cpu/arm920t/ep93xx/speed.c
@@ -39,7 +39,7 @@
 }
 
 /* return FCLK frequency */
-ulong get_FCLK()
+ulong get_FCLK(void)
 {
 	const uint8_t fclk_divisors[] = { 1, 2, 4, 8, 16, 1, 1, 1 };
 	struct syscon_regs *syscon = (struct syscon_regs *)SYSCON_BASE;