global_data: Reduce the size of bus_clk and mem_clk

The bus clock and memory clock are unlikely to go above 4GHz for now, so
reduce the field size to 32 bits.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/asm-generic/global_data.h

@@ -66,11 +66,11 @@ struct global_data {
 	/**
 	 * @bus_clk: platform clock rate in Hz
 	 */
-	unsigned long bus_clk;
+	unsigned int bus_clk;
 	/**
 	 * @mem_clk: memory clock rate in Hz
 	 */
-	unsigned long mem_clk;
+	unsigned int mem_clk;
 	/**
 	 * @env_addr: address of environment structure
 	 *