RPi: Improve board revision detection (#681)

Revision detection is done at runtime, the configure script has been
simplified to reflect this.

drivers/RPi/cpuinfo.h

@@ -0,0 +1,48 @@
+/*
+Copyright (c) 2012-2015 Ben Croston
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of
+this software and associated documentation files (the "Software"), to deal in
+the Software without restriction, including without limitation the rights to
+use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+of the Software, and to permit persons to whom the Software is furnished to do
+so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+
+#ifndef CPUINFO_H
+#define CPUINFO_H
+#if !DOXYGEN
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct
+{
+   int p1_revision;
+   char *ram;
+   char *manufacturer;
+   char *processor;
+   char *type;
+   char revision[1024];
+} rpi_info;
+
+int get_rpi_info(rpi_info *info);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+#endif /* CPUINFO_H */