env: Create a new file for environment functions

At present we have environment.h but this file includes all the
environment-related header files as well as internals such as
default_environment.

It seems desirable to have a new header to hold the commonly used
environment functions, so that most files can avoid including all of this
unnecessary stuff.

Create a new env.h header and move one function over to it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>

include/common.h

@@ -247,10 +247,6 @@ static inline int env_set_addr(const char *varname, const void *addr)
 	return env_set_hex(varname, (ulong)addr);
 }
 
-#ifdef CONFIG_AUTO_COMPLETE
-int env_complete(char *var, int maxv, char *cmdv[], int maxsz, char *buf,
-		 bool dollar_comp);
-#endif
 int get_env_id (void);
 
 void	pci_init_board(void);