Fixes and improvements from Anthony Asterisk

- First in 8051def.h,  it appears the uip_arch-asm.S file was copied from z80 and am unsure it will work properly.  I modified the 8051def.h to prevent the UIP code from using these routines.
- In dma.c the config routine provides access to all of the DMA channel options, except for the word mode flag.  In order to maintain compatibility with any existing code I created a second routine and converted the original routine into a wrapper routine with a fixed word mode value.
- uart.c::uart0_init was missing blocking access to the higher baud rates.  I am not sure why, so I corrected this.
- I also copied over to header files that provide some useful macros from the msp430 cpu.  The files are lpm.h and hwconf.h.  The lpm.h is for switching power modes, I think.  The hwconf.h has various macros for configuring port I/O.  By porting these files the led/button api's can be ported with minimal modifications.

cpu/cc2430/8051def.h

@@ -70,8 +70,13 @@ typedef unsigned int size_t;
  * @see uip_arch.h
  * @see uip_arch-asm.S
  */
-#define UIP_ARCH_ADD32		1
-#define UIP_ARCH_CHKSUM	1
+/*
+ * DO NOT USE UIP_ARCH flags!
+ * uip_arch code was copied from z80 directory but NOT ported
+ */
+
+#define UIP_ARCH_ADD32		0
+#define UIP_ARCH_CHKSUM	0
 #define UIP_ARCH_IPCHKSUM
 
 #define CC_CONF_ASSIGN_AGGREGATE(dest, src)	\