Simpliy Init()-ialization: don't offer enable64, just auto-determine.

Use of 64 bits can be determined when bits are requested.

include/gpio.h

@@ -37,11 +37,11 @@ class GPIO {
 #if RGB_SLOWDOWN_GPIO
             slowdown = RGB_SLOWDOWN_GPIO,
 #else
-            slowdown = 1,
+            slowdown = 1
 #endif
-            bool enable_64 = false
       );
 
+
   // Initialize outputs.
   // Returns the bits that were available and could be set for output.
   // (never use the optional adafruit_hack_needed parameter, it is used

include/led-matrix.h

@@ -267,7 +267,7 @@ class RGBMatrix : public Canvas {
   // convenient as it allows to wait for a change.
   //
   // Returns the bitmap of all GPIO input pins.
-  uint64_t AwaitInputChange(int timeout_ms);
+  gpio_bits_t AwaitInputChange(int timeout_ms);
 
   //-- Double- and Multibuffering.
 

lib/gpio.cc

@@ -147,7 +147,7 @@ namespace rgb_matrix {
 );
 
 GPIO::GPIO() : output_bits_(0), input_bits_(0), reserved_bits_(0),
-               slowdown_(1) {
+               slowdown_(1), enable_64_(false) {
 }
 
 gpio_bits_t GPIO::InitOutputs(gpio_bits_t outputs,
@@ -343,9 +343,8 @@ static bool mmap_all_bcm_registers_once() {
   return true;
 }
 
-bool GPIO::Init(int slowdown, bool enable_64) {
+bool GPIO::Init(int slowdown) {
   slowdown_ = slowdown;
-  enable_64_ = enable_64;
 
   // Pre-mmap all bcm registers we need now and possibly in the future, as to
   // allow  dropping privileges after GPIO::Init() even as some of these