env: clean env_dataflash.c checkpatch and code style

Cleanup the env_dataflash.c checkpatch warnings, errors
and coding style.

Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
diff --git a/include/dataflash.h b/include/dataflash.h
index 96ac097..056e18b 100644
--- a/include/dataflash.h
+++ b/include/dataflash.h
@@ -208,6 +208,8 @@
 extern int addr_dataflash (unsigned long addr);
 extern int read_dataflash (unsigned long addr, unsigned long size, char *result);
 extern int write_dataflash (unsigned long addr, unsigned long dest, unsigned long size);
+extern int AT91F_DataflashInit(void);
+
 extern void dataflash_print_info (void);
 extern void dataflash_perror (int err);
 extern void AT91F_DataflashSetEnv (void);