Add missing "used" attribute to ATTR_INIT_SECTION to ensure functions declared with that meta-attribute are not discarded by the linker.

Add missing function and definition documentation.

LUFA/Drivers/Misc/AT45DB642D.h

@@ -55,8 +55,6 @@
 			#define DF_STATUS_BINARYPAGESIZE_ON             (1 << 0)
 			//@}
 
-			#define DF_MANUFACTURER_ATMEL                   0x1F
-
 			/** \name Dataflash Commands */
 			//@{
 			#define DF_CMD_GETSTATUS                        0xD7
@@ -109,6 +107,9 @@
 			#define DF_CMD_READMANUFACTURERDEVICEINFO       0x9F
 			//@}
 
+			/** Manufacturer code for Atmel Corporation, returned by Atmel Dataflash ICs in response to the \c DF_CMD_READMANUFACTURERDEVICEINFO command. */
+			#define DF_MANUFACTURER_ATMEL                   0x1F
+
 #endif
 
 /** @} */