[AVR32] Clean up OCD register usage

Generate a new set of OCD register definitions in asm/ocd.h and rename
__mfdr() and __mtdr() to ocd_read() and ocd_write() respectively.

The bitfield definitions are a lot more complete now, and they are
entirely based on bit numbers, not masks. This is because OCD
registers are frequently accessed from assembly code, where bit
numbers are a lot more useful (can be fed directly to sbr, bfins,
etc.)

Bitfields that consist of more than one bit have two definitions:
_START, which indicates the number of the first bit, and _SIZE, which
indicates the number of bits. These directly correspond to the
parameters taken by the bfextu, bfexts and bfins instructions.

Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
diff --git a/include/asm-avr32/system.h b/include/asm-avr32/system.h
index dc2d527..c600cc1 100644
--- a/include/asm-avr32/system.h
+++ b/include/asm-avr32/system.h
@@ -35,8 +35,8 @@
 #include <asm/ocd.h>
 #define finish_arch_switch(prev)			\
 	do {						\
-		__mtdr(DBGREG_PID, prev->pid);		\
-		__mtdr(DBGREG_PID, current->pid);	\
+		ocd_write(PID, prev->pid);		\
+		ocd_write(PID, current->pid);		\
 	} while(0)
 #endif