rp2/main: Set CPU frequency to default for the MCU.

Signed-off-by: Damien George <damien@micropython.org>

ports/rp2/main.c

@@ -88,7 +88,7 @@ int main(int argc, char **argv) {
     soft_timer_init();
 
     // Set the MCU frequency and as a side effect the peripheral clock to 48 MHz.
-    set_sys_clock_khz(125000, false);
+    set_sys_clock_khz(SYS_CLK_KHZ, false);
 
     // Hook for setting up anything that needs to be super early in the bootup process.
     MICROPY_BOARD_STARTUP();