imx233: always boost in bootloader

Many imx233 targets boot in a very low performance mode, typically cpu and
dram at 24MHz. This results in very slow boots and very unstable USB
bootloader mode. Since cpu frequency scaling is disabled in bootloader in
rockbox, always make the frequency scaling code available and boost at boot
time.

Change-Id: Ie96623c00f7c4cd9a377b84dcb14b772558cfa4d

bootloader/imx233.c

@@ -141,6 +141,11 @@ void main(uint32_t arg, uint32_t addr)
     system_init();
     kernel_init();
 
+    /* some ixm233 targets needs this because the cpu and/or memory is clocked
+     * at 24MHz, resulting in terribly slow boots and unusable usb mode.
+     * While we are at it, clock at maximum speed to minimise boot time. */
+    imx233_set_cpu_frequency(CPUFREQ_MAX);
+
     power_init();
     enable_irq();