modminer: Raise default/maximum clocks to 210 and 250 respectively

driver-modminer.c

@@ -22,8 +22,8 @@
 #define BITSTREAM_FILENAME "fpgaminer_x6500-overclocker-0402.bit"
 #define BISTREAM_USER_ID "\2\4$B"
 #define MODMINER_MINIMUM_CLOCK    2
-#define MODMINER_DEFAULT_CLOCK  200
-#define MODMINER_MAXIMUM_CLOCK  210
+#define MODMINER_DEFAULT_CLOCK  210
+#define MODMINER_MAXIMUM_CLOCK  250
 
 struct device_api modminer_api;