Maple r3/r5 USB DISC is on PC12

tested on Maple r5, and verified for r3 using

https://github.com/leaflabs/maple/blob/master/maple-r3/maple-r3-schematic.pdf
https://github.com/leaflabs/maple/blog/master/maple-r5/maple-r5-schematic.pdf

Author: dpavlin

config.h

@@ -124,9 +124,9 @@
     #define BUTTON_PIN           8
     #define BUTTON_PRESSED_STATE 1
 
-    /* USB Disc Pin Setup.   USB DISC is PB9 */
-    #define USB_DISC_BANK         GPIOB
-    #define USB_DISC_PIN              9
+    /* USB Disc Pin Setup.   USB DISC is PC12 */
+    #define USB_DISC_BANK         GPIOC
+    #define USB_DISC_PIN             12
 
 #elif defined TARGET_MAPLE_REV5
 
@@ -140,10 +140,11 @@
     /* On the Mini, BUT is PB8 */
     #define BUTTON_BANK      GPIOC
     #define BUTTON_PIN           9
+    #define BUTTON_PRESSED_STATE 1
 
-    /* USB Disc Pin Setup.   USB DISC is PB9 */
-    #define USB_DISC_BANK         GPIOB
-    #define USB_DISC_PIN              9
+    /* USB Disc Pin Setup.   USB DISC is PC12 */
+    #define USB_DISC_BANK         GPIOC
+    #define USB_DISC_PIN             12
 
 #elif defined TARGET_GENERIC_F103_PC13